Physics/Questions Answered by Expert Kevin Johnson
| Subject | Date Asked |
| Question on Pressure | 8/28/2009 |
| Q: I have not opportunity to study phisics in my country so I ask you a very dumb question... but I ... A: Sorry for the late answer, I was away for the weekend. For the balloon under water you do not need ... | |
| massless | 8/27/2009 |
| Q: I'm curious, are there particles that contain no mass? By that I mean, is this proven or is it ... A: Einstein's famous formula E=mc^2 expresses the equivalence of mass and energy: If you accelerate a ... | |
| Light as surface | 8/25/2009 |
| Q: This might be a dumb question, but can light ever be used as a surface on-which light can be ... A: no, just providing a projection surface for a movie would not work with a "sheet" of light or laser ... | |
| microwave water | 8/25/2009 |
| Q: A lot of health food people feel that microwaves damage food. I heard from one person that if you ... A: microwave radiation is electromagnetic radiation of wavelengths between radio waves and infrared ... | |
| plasma | 8/23/2009 |
| Q: How will you create a plasma state? How it works? Is plasma state a very good conductor of ... A: a plasma is a state where the kinetic energy of the particles is so high that the electrons cease to ... | |
| Question on Pressure | 8/22/2009 |
| Q: I have not opportunity to study phisics in my country so I ask you a very dumb question... but I ... A: Since the water pressure increases with increasing depth, the pressure difference between the ... | |
| theoretical physics | 8/21/2009 |
| Q: what is the physical significance of commutation relation in quantum physics? A: If two operators commute, i.e. their commutator is equal to zero, that means that you can measure ... | |
| Light as surface | 8/21/2009 |
| Q: This might be a dumb question, but can light ever be used as a surface on-which light can be ... A: Since light has not only particle nature (it consists of photons) but it also has wave nature, it ... | |
| Electric current | 7/24/2009 |
| Q: When you touch an electric wire while standing on the ground, you get shocked! How an electric ... A: empty space is a perfect insulator in the sense that is does not supply any freely movable charges ... | |
| lenght of a curb lever | 7/14/2009 |
| Q: would you pls explain me ; if i use a curb shape lever rather than a hard straight one .considering ... A: the lever length is the straight distance from the fulcrum to the point where the force is applied. ... | |
| Artificial CG on Machines or bodies. | 7/13/2009 |
| Q: Can we create an artificial “CG” point on a body. Suppose we have a table with two legs and it is ... A: I presume by "CG" cou mean the center of gravity. The center of gravity is a mathematical entity ... | |
| Wave | 7/12/2009 |
| Q: I've finshed my 12th grade. Wave is a form of disturbance in any media. Light travels through vacuum ... A: this is a very general question. A wave is anything that fits the mathematical description of a ... | |
| Electric current | 7/11/2009 |
| Q: When you touch an electric wire while standing on the ground, you get shocked! How an electric ... A: Voltage: http://en.wikipedia.org/wiki/Voltage Yes, the current can pass through the particles and ... | |
| Electric current | 7/8/2009 |
| Q: When you touch an electric wire while standing on the ground, you get shocked! How an electric ... A: Indeed the ground (earth, stone, especially water) is an electric conductor, not as good as metals, ... | |
| Battery and Leyden jar | 7/7/2009 |
| Q: What's the difference between battery and Leyden jar? A: The Leyden jar is more similar to a capacitor than a battery. In a Leyden jar, the charges are ... | |
| electron | 7/7/2009 |
| Q: How an electron revolve around the nucleus? If it is in an elliptical orbit, the nucleus is one ... A: the so-called Rutherford electron shell model which describes the electron as orbiting the nucleus ... | |
| Light | 7/6/2009 |
| Q: Can you tell me what kind of light can't get through water no matter whether it is visible light or ... A: Visible light and ultraviolet light are those parts of the electromagnetic spectrum that have the ... | |
| candle light | 7/5/2009 |
| Q: When you light up a candle, the flame will glow in a triangle like shape. Why can't it take any ... A: a burning candle that is lit in a zero gravity environment (e.g. in the International Space Station) ... | |
| nucleus | 7/1/2009 |
| Q: I am a high school student & I have a question. If neutrons exert only attractive force why don't we ... A: Neutrons are electrically neutral, so the only forces which they interact with one another are ... | |
| physics | 6/29/2009 |
| Q: according to "newton law of gravitation" Force is inversily ... A: The complete version of Newton's law of gravity is the following: "Every point mass attracts every ... | |
| Deja vu | 6/23/2009 |
| Q: Kevin my question is kind of strange, but do you think it could be possible that deja-vu is linked ... A: I do not see any possibility for time travel in established physics theory. I do not subscribe to ... | |
| atom | 6/21/2009 |
| Q: How the Rutherford's atomic model defects was overcame by Bohr? i.e., the electron orbits. Explain ... A: In Rutherford's atomic model it was a puzzle that the electrons that were accelerated did not emit ... | |
| atom | 6/20/2009 |
| Q: Read this example before reading the question. Ex: Light travels in the form of electromagnetic ... A: While sound waves travel through a medium (e.g. air, water, railroad tracks), there is no such ... | |
| atom | 6/19/2009 |
| Q: What is a charge and what it is made of? In protons and electrons, you will find a least amount of ... A: Indeed when scientists discovered quarks as the constituents of protons, they found these new ... | |
| atom | 6/17/2009 |
| Q: What is a charge and what it is made of? In protons and electrons, you will find a least amount of ... A: Charge is not "made of" something else, it is a property of elementary particles such as electrons ... | |
| Leverage | 6/16/2009 |
| Q: I have a farm tractor that can lift 1800 kilograms at the 3 point linkage at the rear of the ... A: I would need more information to answer your question yes or no. What I would need to know is the ... | |
| lowering pressure during the evaporation process | 6/14/2009 |
| Q: Iwould like to know if lowering pressure during the evaporation process of a certain liquid will ... A: Bubbles form when the local pressure (at the exact point in the liquid where a bubble forms) drops ... | |
| Styrofoam reaction to temperature changes? | 6/13/2009 |
| Q: Recently I had a Styrofoam cup of cherry kool-aid that I stuck in the freezer overnight. When I ... A: Styrofoam cups are not perfectly water-tight (or kool-aid-tight in your case). They have microscopic ... | |
| What strings are made of? | 6/13/2009 |
| Q: Based on string theory, a string is an object with a one-dimensional spatial extent. But what this ... A: I am afraid I was not quite clear enough in distinguishing between two different concepts: 1) ... | |
| physics | 6/10/2009 |
| Q: If a simple pendulum is kept in space then what is its time period? A: I am not sure what you mean by "kept in space". If you mean the pendulum is in outer space, where ... | |
| Polarized sunglasses | 6/9/2009 |
| Q: Could you explain the following sentance. Since the most outdoor surfaces are horizontal, Polaroid ... A: Polarized (!) sunglasses are made by applying a polarization filter to the glasses that eliminates ... | |
| What strings are made of? | 6/8/2009 |
| Q: Based on string theory, a string is an object with a one-dimensional spatial extent. But what this ... A: Indeed the "strings" of string theory are mathematical models that behave in a way that resembles ... | |
| Oil truck shape | 6/6/2009 |
| Q: sir, Why the shape of an oil truck oval?Is here any reason? I'll be very glad if u give the ans. ... A: In a liquid (or gas), the pressure on the walls is equal in all directions. So if you would use a ... | |
| straw madness | 6/6/2009 |
| Q: hey, I think its time to ask a expert on the matter now. I apoly for my bad English writing at ... A: Sorry you had to wait so long for the answer, I was very busy the past few days. Now to yourWhen ... | |
| physics | 6/5/2009 |
| Q: im a first year university student and need help with the following physicsIf a beam of unpolarised ... A: Total reflection occurs when light hits a boundary at an angle of incidence (with respect to the ... | |
| Electric fields Physics | 6/4/2009 |
| Q: Would you please see the attached file and help? Thank you. A: The Lorentz force _F of an electric field _E on a charge q is _F = q * _E (The _ denotes a ... | |
| Vortex vs. centrifugal force. | 6/4/2009 |
| Q: After gaining an understanding of how a centrifuge works, this experiment has always confused me: ... A: In the experiment you describe the dominant force is not gravity or buoyancy (as in a centrifuge), ... | |
| physics | 6/3/2009 |
| Q: What are some economic and political ways Albert Einstein impacted the world? A: This is not really a physics question, so please understand the following answer not as "expertise", ... | |
| Physics | 6/2/2009 |
| Q: Respected sir, I am a student of class 12, I hope you have time for this. We say that ... A: The atomic model that you are probably thinking of, the planetary model where electrons orbit the ... | |
| 2 dimensional physics | 5/4/2009 |
| Q: Hey, Kevin, I'm puzzled by a question, can you guide me through the process? A golf ball is hit ... A: At the beginning of its trajectory, the golf ball of mass m has a velocity v=75m/s and thus the ... | |
| energy | 5/2/2009 |
| Q: I have a question about energy. What exactly is energy? I know its defined as the ability to do ... A: Energy can take many forms, for example kinetic energy, potential energy, thermal energy, elastic ... | |
| fusion of dissimilar atoms | 5/1/2009 |
| Q: I always hear how hydrogen fuses into helium and when it runs out then the sun becomes a red giant ... A: The main reaction going on inside the sun is the fusion of two hydrogen nuclei to one helium ... | |
| Science | 2/25/2009 |
| Q: How do you measure your pulse rate? A: The human pulse rate is usually measured in heartbeats per minute. This can be done by feeling your ... | |
| Science | 2/25/2009 |
| Q: How does your pulse rate affect the heart? A: A hint for the future: Please ask all of your questions at once. Some of us experts have set a ... | |
| physics | 2/24/2009 |
| Q: why neutron shows magnetic moment ANSWER: Hello Farid Sabir, The neutron's magnetic moment has ... A: Excellent question! The neutron consists of three quarks, one up-quark (charge +2/3e) and two ... | |
| Dynamics Question | 2/23/2009 |
| Q: A football quarterback stands at 'A'. At the instant the quarterback throws the football, the ... A: Your first two equations are correct, the third is a consequence of the first and the fact that Y=0 ... | |
| The Physics of Color | 2/23/2009 |
| Q: What dimension is a color? The only way to SEE color is at least on a 2D scale. But does it have to ... A: From a physicists point of view, color is the wavelength of light in the visible part of the ... | |
| light filters | 2/20/2009 |
| Q: i'm doing a science fair project on light and light filters. I performed an experiment with light ... A: Additive mixture of colors happens when two or more light sources of different colors are combined. ... | |
| physics NYC - waves | 2/20/2009 |
| Q: is it possible to have a net wave of zero? if 3 waves (amplitudes of 0.3,0.5 and 0.8) were ... A: Yes, it is possible for waves to interfere destructively, i.e. in a way that the sum of their ... | |
| spring | 2/19/2009 |
| Q: If 2 ends of a spring balance are simultaneously pulled with equal force, what happens? What will be ... A: If you apply a force only to one end of a spring balance (the other end is free!), then the whole ... | |
| question about visualizing harmonics on a string | 2/18/2009 |
| Q: When you get the chance, I have another question for you about visualizing harmonics. When I pluck ... A: I am not quite sure what you mean by visualizing harmonics. If you want to know how the string ... | |
| question about oscillation, equilibrium, and transverse waves | 2/16/2009 |
| Q: I'm confused about the meaning of the word "equilibrium" when it is used in explanations of objects ... A: Your hunch is probably quite right: It is a matter of how we normally experience things. When you ... | |
| Batteries | 2/16/2009 |
| Q: I have a question that i came across in a text book and I tried to work it out but i'm not sure ... A: The capacity rating of a battery is (in principle) the product of the constant discharge current ... | |
| Speed of Light | 2/13/2009 |
| Q: Is it possible to exceed the speed of light? My physics teacher though that she saw an article that ... A: It depends on what you mean exactly by "exceeding the speed of light". There have been several ... | |
| ESD in a cold weather | 2/12/2009 |
| Q: Recently I was in China freezing at -10deg. I managed to get around 20 ESD shots at least a day when ... A: Weather with below-freezing temperatures leads to two things: Warmer clothing (woolen or synthetic) ... | |
| physics | 2/12/2009 |
| Q: why neutron shows magnetic moment A: The neutron's magnetic moment has been measured to be −1.9130427(5)μ where µ is the ... | |
| Hammer Throw Puzzler.??? | 2/11/2009 |
| Q: .. Below is a link that shows a blond Russian lady Hammer thrower (ther are about 4 other ... A: sorry, my mistake for not having made it clear what I mean: I did not want to imply that the hammer ... | |
| Hammer Throw Puzzler.??? | 2/11/2009 |
| Q: .. Below is a link that shows a blond Russian lady Hammer thrower (ther are about 4 other ... A: Conservation of angular momentum tells us that without an external torque the rotation direction of ... | |
| Bow and Arrow | 2/10/2009 |
| Q: We have invented a crossbow capable of extreme accuracy (same hole at 50 yards every time), and a ... A: I do not think this would work like you would hope. The arrow or bolt initially lies in a barrel, ... | |
| Electricity | 2/10/2009 |
| Q: Sir, what is the difference between potential difference and voltage? A: In electrodynamics "potential difference" and "voltage" are synonymous, they mean the same thing. ... | |
| Time dilation | 2/9/2009 |
| Q: there, I'm a bit confused about the equation for time dilation due to relative motion. A standard ... A: Time dilation is about time intervals delta t' and delta t: delta t' = delta t * (Lorentz factor) ... | |
| particles charge | 2/8/2009 |
| Q: How do caheged particles lose their charge? Is it possible to place charged particles in a container ... A: Elementary particles (electrons, protons, neutrons, etc.) retain their charges until are annihilated ... | |
| melt down | 2/8/2009 |
| Q: I am a theologian exploring the issue of 'melt-down' theologically in connection with a theology of ... A: The term "meltdown" originally only referred to the nuclear meltdown, an accident in a nuclear power ... | |
| bernoulli | 2/7/2009 |
| Q: In the steady flow, what is the factor that decreased the pressure and increased the velocity when ... A: when the cross section of a steady flow is reduced, then the velocity must increase to provide for ... | |
| science fair project - surface affectinng bounce height | 2/6/2009 |
| Q: Johnson, For my sciecne fair project this year i've decided to answer the question of, "Does the ... A: I am no "Dr.", yet. The "primary source" for every scientist is the experiment. Since the effect ... | |
| physics re: ramps and levers | 2/6/2009 |
| Q: I am studying for my ASVAB to join the Coast Guard and due to being 30 years old I HAVE to score ... A: Your reasoning and calculations are absolutely correct and you seem to have understood the ... | |
| water pressure | 2/4/2009 |
| Q: I left school a long time ago, is my memory failing or do I remember correctly. If you put your ... A: What you remember quite right is called Bernoulli's principle: An increase in fluid velocity ... | |
| physics | 1/29/2009 |
| Q: if light has a partical nature then how it passes throug the glass . A: Atoms are composed of their nucleus and a large, "empty" volume around the nucleus where electrons ... | |
| Rotational motion question | 1/26/2009 |
| Q: I am wondering, if the world's populations move to the North and South Poles, would the length of a ... A: The length of a day is defined in modern times as 24 hours, or 1440 minutes, or 86400 seconds. And ... | |
| Quantum Mechanics | 1/25/2009 |
| Q: I understand that two main theories for explaining quantum mechanics are the Copenhagen theory and ... A: The Copenhagen interpretation of quantum mechanics is, philosophically speaking, a positivistic ... | |
| Falling objects | 1/24/2009 |
| Q: Why is that 3 different objects with different masses reach the ground when you drop them at the ... A: The force of gravity is of course proportional to the mass of an object, so an object of double the ... | |
| gravitational force | 1/23/2009 |
| Q: I recently asked a question regaurding my 8th grade homework. my question is: The gravitational ... A: You and your parents most probably have good reasons why you are homeschooled, but if you cannot ask ... | |
| reality seems too stable for a quantum foundation | 1/19/2009 |
| Q: i am not a physicist but i have listened to science programmes that talk about the non location of ... A: This question touches the realm of philosophy: If nobody is looking, is the moon still there? ... | |
| Reverse Bias | 1/19/2009 |
| Q: Respected Sir, I wANTED TO KNOW WHY NO CURRENT FLOWS IN REVERSE BIAS.THOUGH WE SAY AT SATURATION ... A: Reverse-biased refers to how a diode is used in a circuit: the voltage at the cathode is higher than ... | |
| Time | 1/18/2009 |
| Q: This might be a strange question but could time be omni-directional? P.S. I may be asking you alot ... A: Time as we experience it is uni-directional, i.e. it only flows in one direction: towards "later", ... | |
| reality seems too stable in a quantum world | 1/16/2009 |
| Q: i am not a physicist but i have listened to science programmes that talk about the non location of ... A: The non-locality of quantum mechanics is a phenomenon that is most prominently observable with ... | |
| work | 1/13/2009 |
| Q: Is the force at the center of the earth is zero and if so why we didn’t choose the center as a ... A: Yes, the (gravitational) force F at the center of the Earth is zero. This means that the first ... | |
| work | 1/13/2009 |
| Q: Why did energy (work) depends on the force and displacement and not other parameters A: Work is defined as displacement times force along the path of displacement. This definition makes ... | |
| Rotation | 1/12/2009 |
| Q: Respected sir, I hope ypou have time for this: Why is't the centrifugal force experienced by a body ... A: "centripetal force = centrifugal force" is only true for a flying orbit. While standing on the ... | |
| laser | 1/10/2009 |
| Q: explain why laser action could not occur without population inversion between atomic level? A: If there is no population inversion, then stimulated absorbtion is more prabable than stimulated ... | |
| compton effect | 1/10/2009 |
| Q: why we don't observe compton effect with visible light? A: The change in wavelength (delta l) of the scattered photon undergoing Compton scattering is delta l ... | |
| Physics of vehicles | 1/9/2009 |
| Q: A car is moving in a circle on a sloped road. The car accelerates every five seconds and then ... A: you have three forces acting on the car of mass m (the mass will cancel out in the final equations): ... | |
| physics - acceleration through space | 1/9/2009 |
| Q: Someone asked thisWhat is the speed of a fly on a moving train? And it was answered thusly: The ... A: Acceleration is velocity change per time. Since the time it takes to change from 190km/s to 250km/s ... | |
| potental energy | 1/7/2009 |
| Q: why we chosen the infinity as a Reference instead of the center of the earth in calculating the ... A: The reference point for potential energy is arbitrary - it has no physical meaning, since only ... | |
| Mechanics and Kinematics | 1/5/2009 |
| Q: Repected sir i am a mukul of grade 11 I have a lot of questions. I hope you have the time to answer ... A: 1) The rotation of Earth does not affect gravity, but the centrifugal force, that acts outwards on ... | |
| Conservation of Momentum | 1/5/2009 |
| Q: I am in my first year in college, and I am a bit confused about conservation questions.... A ... A: Momentum is conserved in situations where there is no outside force. Since there is an outside force ... | |
| Special Relativity | 12/30/2008 |
| Q: I've just started learning Special Theory of Relativity, and I have several questions to ask... 1. ... A: Sorry for the long wait. 1. An observer in a resting inertial system would say a clock travelling ... | |
| Flotation/Suspension priniciples | 12/29/2008 |
| Q: My knowledge level: Beginner This is not homework, I'm trying to make better fishing lures. Hi, ... A: You would have to have the flotation device displace *exactly* its own weight in water for it to be ... | |
| Theory of Relativity | 12/28/2008 |
| Q: what is great abt theory of relativity and why it so imortant??? A: Einstein's theory of relativity is a meta-theory in the sense that all physics theories operate in a ... | |
| PHASE RULE | 12/20/2008 |
| Q: WHY VAPOR CONVERTS INTO ICE DIRECTLY BELOW THE TRIPLE POINT? WHAT IS MEAN BY TRIPLE POINT ... A: At a given combination of pressure and temperature a given substance can only exist in one phase, it ... | |
| Regarding Newton's 3rd law | 12/18/2008 |
| Q: I have a simple question but it is confusing for me. According to Newton's third law, For every ... A: You quoted the brief and simplified formulation of Newton's third law. The more precise original ... | |
| special glasses | 12/17/2008 |
| Q: how can i see behind the things? for example i want to see if someone carrying a weapon behind his ... A: there is no such thing as "x-ray glasses" that let you see through clothing or walls. Seeing is a ... | |
| Kinetic energy | 12/17/2008 |
| Q: As a follow up question, Ref yr earlier reply:Without friction, you would not do any work "pushing" ... A: Yes, if a mass has kinetic energy, then work has been done on it earlier to achieve this state. ... | |
| Using lightning energy | 12/16/2008 |
| Q: I would like to know whether it is possible to utilize the energy from lightning for useful ... A: Lightning strikes are much too unpredictable to make serious use of them as an energy source. Also ... | |
| forces | 12/16/2008 |
| Q: I have a follow up question. Ref you earlier response:If you are moving the backpack at a constant ... A: Without friction, you would not do any work "pushing" a trolley, either. But since friction exerts a ... | |
| Spring Potential Energy | 12/15/2008 |
| Q: I have a problem and I can not solve it. We have a simple spring.We compress it and fix the current ... A: The potential energy stored in the whole spring is the sum of potential energies in atomic bonds ... | |
| Waves and oscillations | 12/13/2008 |
| Q: Respected sir, I am a student of grade 11 What is the difference between an oscillatory motion and ... A: An oscillatory motion can be any motion that is periodic, i.e. it returns to the same position and ... | |
| Buoyancy calculation | 12/11/2008 |
| Q: I have an 18" sealed hollow air filled tube floating in a bath of water supporting a load of 100lbs ... A: The buoyant force is equal to the weight of the displaced volume of water. This is the Archimedean ... | |
| Electric charges | 12/10/2008 |
| Q: if a negatively charged particle enters a uniform magnetic field with its velocity perpendicular to ... A: In a uniform magnetic field the force on a charged particle is perpendicular on its velocity vector. ... | |
| Work Done | 12/8/2008 |
| Q: I read in a text book that if I lift a backpack,I am doing work (OK agree)when the pack is on my ... A: Not every movement is related to work done. Work is distance times force along the line of ... | |
| Air vs. Hydraulic Oil Molucule size | 12/3/2008 |
| Q: In testing Hydraulic Reservoirs for a customner the question came up... which is larger... the air ... A: Oil is a complex organic chemical with long hydrocarbon chains, while Air is mainly Oxygen (O2) and ... | |
| Light / data flow | 12/3/2008 |
| Q: I have a general knowledge of physics and computers, but my question is simple: Is there a physical ... A: For a single signal channel the limit on data flow is determined by the quality of the channel (e.g. ... | |
| Gravity | 12/3/2008 |
| Q: I just read this in one of my books and I don't understand how it could happen..."Theoretically a ... A: You are right, centrifugal forces are directed away from the center of rotation. But this can be ... | |
| density of liquid | 12/2/2008 |
| Q: . ^^. the problem is this: "A 200-ml flask is filled with an unknown liquid. An electronic balance ... A: > is the volume of the liquid also the same as the volume of the flask? Yes, I would believe that ... | |
| Relativity | 11/30/2008 |
| Q: my question is when we are dealing with moving laser beams at the speed of light, and we want to ... A: The Lorentz transformation is a vector transformation. It transforms the space-time four-vector of ... | |
| billiards, kinetic energy | 11/26/2008 |
| Q: i an new and i need help with two questions. 1) In billiards(pool), is it possible for the cue ball, ... A: 1) For collisions you need to take into account the conservation of total momentum and the ... | |
| GRAVITATION | 11/26/2008 |
| Q: WHAT IS THE EFFECT OF TEMPERATURE ON GRAVITATION? EXPLAIN. A: In principle temperature has no effect on gravity. Gravity only depends on the masses involved and ... | |
| wave interference | 11/25/2008 |
| Q: I am doing a physics experiment,connecting two speakers to emit same sound frequency to produce node ... A: The two speakers that emit the same frequency produce as their interference pattern a so called ... | |
| Energy | 11/24/2008 |
| Q: Why force can't be an energy? Although I know that the force has to multiply the distance so as to ... A: Both force and energy are somewhat abstract concepts, since they are only measurable by the effect ... | |
| momentum | 11/23/2008 |
| Q: I'd like to ask you a few questions; can you tell me, what unit is momentum measured in? I thought ... A: Momentum does not have a unit of its own like force (Newton), distance (meter), time (second) or ... | |
| finding velocity using force | 11/23/2008 |
| Q: If I am given the force exerted on a object, the mass of the object, and the amount of time the ... A: Newtons second law of motion tells you that a force F acting on an object of mass m causes it to ... | |
| surface | 11/23/2008 |
| Q: I wanted to ask that why we are able to penetrate(go into) water or any other fluid. When we stand ... A: In a solid the molecules are arranged with what is called "long range order", which means that they ... | |
| uncertainty principle/observer effect | 11/20/2008 |
| Q: Why can't you measure both the location and velocity of a particle at the quantum level? What ... A: Every measurement is an interference with the system you are measuring. For macroscopic systems this ... | |
| bose einstein condensate | 11/20/2008 |
| Q: an i right in thinking that bose einstein condensate is essentially pure probability in material ... A: I think perhaps you have confused two related but different concepts in your thinking. There are ... | |
| Energy | 11/19/2008 |
| Q: A woman stands on the edge of a cliff and throws a stone vertically downward with an initial speed ... A: This sounds very much like a homework question - and I do not give homework solutions. But I can ... | |
| Chemical explosions and particle physics | 11/13/2008 |
| Q: My level : high school senior. If you mix oxygen molecules and hydrogen molecules together and ... A: There is a new molecule that is formed by the chemical reaction. It is not very meaningful to say ... | |
| Chemical explosions and particle physics | 11/13/2008 |
| Q: My level : high school senior. If you mix oxygen molecules and hydrogen molecules together and ... A: The original state (2 H2 + O2) has a higher potential energy than the bound state (2 H2O), so energy ... | |
| fields versus forces | 11/13/2008 |
| Q: Level: college freshman...If gravity is caused by the warping of space by mass, and therefore a ... A: The "strange" thing about quantum field theories is that the classical fields are quantized, i.e. ... | |
| condensation | 11/12/2008 |
| Q: This may be stupid to you, But I just want to know exactly why and if I can stop it. I built this ... A: While heated air might feel dry and indeed has a lower relative humidity, this is a result of the ... | |
| Acceleration in space | 11/12/2008 |
| Q: Mr. Johnson, I just read a great response to a question concerning acceleration in space. In the ... A: When you turn off the engine you are shutting off the force, and thus also the acceleration. The ... | |
| condensation | 11/12/2008 |
| Q: This may be stupid to you, But I just want to know exactly why and if I can stop it. I built this ... A: The warmer a volume of air is, the higher its capacity for water vapor. So while you heat the air ... | |
| Work and Energy | 11/11/2008 |
| Q: Why is it tiring to push hard against a solid wall even though I am doing no work? ANSWER: Hello ... A: Work is always done by a force on an object. You are not doing work on the wall. This is probably ... | |
| Work and Energy | 11/11/2008 |
| Q: Why is it tiring to push hard against a solid wall even though I am doing no work? A: This has to do with the way muscles work. Muscles are bunches of filaments which can either contract ... | |
| Danger - High Voltage | 11/10/2008 |
| Q: why then do signs danger-high voltage" rather than "danger" high current? A: In facilities where there is a sign "Danger - High Voltage" there is a high electrical potential ... | |
| Pursuit curve | 11/10/2008 |
| Q: Here is a problem I can't solve: A dog is standing in "B" point on the "X" axis. It's owner is ... A: The term "dog curve" is not so precise. It could refer to what French speakers call "courbe de ... | |
| AMANDA and ANITA projects | 11/7/2008 |
| Q: I came across this physics blog whilst reading and learning about particle smashers: ... A: The AMANDA and ANITA projects are neutrino detectors. They do not produce any particles (or smash ... | |
| heat | 11/6/2008 |
| Q: What liquid has the highest specific heat? This came up during a conversation and the person who ... A: The specific heat capacity of a substance is the amount of heat (energy) you must give it in order ... | |
| electrons | 11/3/2008 |
| Q: the basis of quantum mechanics is that when electrons jump from one orbit to another, light energy ... A: I wrote that electrons *in an excited state* can jump to a lower energy state and thereby emit ... | |
| Kinetic energy in vehicle collisions | 11/2/2008 |
| Q: I saw a similar question you answered recently, but wondered if you could help with this. Scenario - ... A: Sorry for the long wait for my answer. I was unexpectedly very busy. To solve collision problems, ... | |
| electrons | 11/2/2008 |
| Q: the basis of quantum mechanics is that when electrons jump from one orbit to another, light energy ... A: Electrons in an excited state can jump to a lower energy state by two mechanisms: 1) spontaneous: ... | |
| Dichroic mirrors & filters | 10/31/2008 |
| Q: As I understand it, dichroic filters pass selected wavelengths whilst reflecting others, whereas ... A: Dichroic mirrors and dichroic filters are actually the same. Depending on what their main function ... | |
| kepler's law | 10/30/2008 |
| Q: Kepler's law said that the earth's velocity changes at perihelion and aphelion it mean it is ... A: Actually, it follows from Kepler's second law that the Earth's velocity is highest at its perihelion ... | |
| Help! momentum | 10/28/2008 |
| Q: Sir could u help me with this problem, ive tried it a couple of times. If you could help tht would ... A: You need to use the conservation of momentum for problems dealing with recoil. The momentum p of a ... | |
| Virtual photons | 10/27/2008 |
| Q: My level : High school physics plus lots of reading of undergraduate textbooks in physics. Virtual ... A: Next to virtual photons there are of course also real photons, photons that carry energy from one ... | |
| Virtual photons | 10/27/2008 |
| Q: My level : High school physics plus lots of reading of undergraduate textbooks in physics. Virtual ... A: For all matter and forces there are two views you can take: the particle view and the field or wave ... | |
| third law of motion | 10/27/2008 |
| Q: suppose a box is lying on ground with mass m so it will exert a force of mg on earth and the earth ... A: I think you got it right, but I am not 100% sure. To clarify things a bit: While the box and the ... | |
| Center of mass | 10/26/2008 |
| Q: I am asking about the center of mass relative to particles moving with the speed of light, such as ... A: Yes, with relativistic motions you use the same rules for calculating the center of mass. But I ... | |
| Center Of Mass | 10/24/2008 |
| Q: Does the center of mass always travel with the constant velocity and angular momentum? When does the ... A: The center of mass of an object travels with constant velocity as long as no external forces act on ... | |
| impulse...momentum etc | 10/24/2008 |
| Q: Hey Mr. Johnson, I have been trying this question over and over, finally I give up..if you would ... A: What you need to use to solve this problem is: 1) Acceleration is velocity difference (final ... | |
| third law of motion | 10/23/2008 |
| Q: suppose a box is lying on ground with mass m so it will exert a force of mg on earth and the earth ... A: The Earth exerts two forces on the box: 1) Gravity, which pulls the box downwards. 2) The suspension ... | |
| double slit laser experiment | 10/22/2008 |
| Q: Has the double slit quantum experiment ever been done in a vacuum ? How do they know that the photo ... A: A perfect vacuum is impossible to create due to technical limits, but yes, the double slit ... | |
| car impact physics | 10/22/2008 |
| Q: Question Hello Kevin, Would you be able to explain what happens when 2 cars collide head on when ... A: From the perspective of a colliding car it makes no difference if it collides with a wall or with ... | |
| electromagnetic spectrum | 10/22/2008 |
| Q: I am GCSE level so my knowledge is somewhat limited and this may seem like a silly question! But I ... A: If the human body is exposed to a sufficient intensity of visible light, it becomes visible to ... | |
| Theoretical limits to high and low energy photons | 10/21/2008 |
| Q: Gamma rays are characterised as electromagnetic radiation having the highest frequency and energy, ... A: Light, or electromagnetic radiation is subject to the wave-particle duality, i.e. depending on how ... | |
| Energy -Physics | 10/21/2008 |
| Q: Hey Mr.Johnson, I wuold really appreciate if you would be able to help me with the prblem..with an ... A: part A: Work is force times distance parallel to the force. The force (weight) is downwards, and ... | |
| planks constant | 10/18/2008 |
| Q: If the energy of one photon is equal to Planks constant times the speed of light divided by the ... A: You are right that the energy E of a photon is Planck's constant h times the speed of light c ... | |
| Energy can't be created | 10/16/2008 |
| Q: If energy cant be created how does a punch work. ANSWER: Hello Phil, I would like to answer your ... A: Let's take a look at what happens in all the stages of a punch thrown and asking: Where does the ... | |
| Energy cant be created | 10/16/2008 |
| Q: If energy cant be created how does a punch work. A: I would like to answer your question, but please specify which kind of punch you mean: 1) the tool ... | |
| water pressure | 10/15/2008 |
| Q: the question is as follows. Lets say I have a funnel 10 feet tall and a cylinder 10 feet tall, both ... A: The Hazen-Williams equation is detailed here: http://en.wikipedia.org/wiki/Hazen-Williams_equation ... | |
| water pressure | 10/14/2008 |
| Q: the question is as follows. Lets say I have a funnel 10 feet tall and a cylinder 10 feet tall, both ... A: Let's start with the basics. Pressure is force per area: p = F / A The pressure in an ... | |
| Basic Physics Problem | 10/13/2008 |
| Q: I have tried and tried and I have figured out the first half of the answer to the question but am ... A: The cork in still water represents a harmonic oscillator: If you excite a small motion (e.g. by ... | |
| heat\ light aborbtion and colours | 10/13/2008 |
| Q: I'm in grade 11 and Currently doing my EEI (extended experimental investigation) and i need to ... A: Red light has a longer wavelength than blue light. Now if white light, which is a mixture of all ... | |
| projectiles | 10/12/2008 |
| Q: how would i go about solving the following problem? (if you get me started, then I'll be able to ... A: You said you wanted me to get you started and you would be able to find the answer. This is just ... | |
| Microwave EMF field | 10/12/2008 |
| Q: Professor Johnson, I am a student in grade 11 in Canada. I have had a very fond interest in ... A: I am not a professor (well, not yet). When you interpret the measurements of your field gauge, you ... | |
| scalar product | 10/11/2008 |
| Q: Can a scaler product of two vectors be negative? A: Yes, the scalar product of two vectors can be negative. Example: (1,-2) * (-3,4) = 1*(-3) + (-2)*4 ... | |
| Hazards of 400 nm lasers? | 10/8/2008 |
| Q: What hazards -- other than thermal burns -- does a 400-nanometer-wavelength continuous [i.e. ... A: Light of 400nm wavelength is just below the violet end of the visible spectrum, so it would be ... | |
| How does a compass work? | 10/7/2008 |
| Q: how does a compass work??why does a compass point north??? A: A compass has a needle that is magnetized. This needle is suspended so that it can rotate freely and ... | |
| Relative Velocity | 9/30/2008 |
| Q: A boy standing in a lift that is moving (a) upwards and (b) downwards at a constant speed of 5 m/s ... A: you correctly calculated the time it takes for the ball to return to the position it was released at ... | |
| unit conversion | 9/30/2008 |
| Q: sound travels 1100 ft/sec which equals _____ mph? A. 660 B. 700 C. 750 D. 920 E. none A: for unit conversions you can use google calculator: http://www.google.com/search?q=1100+ft/s+in+mph ... | |
| Class of Machines | 9/28/2008 |
| Q: I was wondering if a wrench is a second class machine. And what happens if it is a closed wrench ... A: If you needed to know what class of lever, you should have asked me what class of lever. You asked ... | |
| light properties | 9/28/2008 |
| Q: We all know that a beam of light can be re-directed by a physical object like a mirror. My question ... A: Light interacts with matter, but it does not interact with other light from a different source. ... | |
| heat and temperature | 9/26/2008 |
| Q: "if we bring two objects having different temperatures in contact with each other,heat flows from a ... A: Sorry, but I do not know what you mean by "X standard". If two bodies of different temperature are ... | |
| heat and temperature | 9/25/2008 |
| Q: "if we bring two objects having different temperatures in contact with each other,heat flows from a ... A: Heat will flow from one object to the other until they are at the same temperature, at thermodynamic ... | |
| friction | 9/25/2008 |
| Q: A force of 180 N is required to slide a loaded box along a horizontal floor. If the Coefficient of ... A: as this is clearly a homework question you will certainly understand that I will not give you a ... | |
| Physics | 9/23/2008 |
| Q: A process, developed in Sweden, called promesis, has been developed as an alternative for cremation ... A: It depends on what you consider 'light' vibrations or 'vigourous' shattering. My estimate is that ... | |
| current - voltage - power - resistance | 9/23/2008 |
| Q: I want to ask that whether I is directly proportional to V(V=IR), or it is indirectly to P(power) ... A: A rheostat is a variable resistor. If you turn the knob (or move a slider) the resistance changes. ... | |
| Questions on many fields of Physics continued | 9/22/2008 |
| Q: 4) Potential Energy has the same sign as internal energy, does this mean that potential ... A: 4) Potential energy can be thought of as energy stored within a physical system. It is called ... | |
| Questions on many fields of Physics | 9/22/2008 |
| Q: I have some questions, hope you can help me. 1) When multiplying vectors, what is the difference ... A: 1) The dot product of two vectors gives a scalar quantity, the cross product gives a vector as ... | |
| gravitation | 9/21/2008 |
| Q: why is the gravitational potential enrergy of a body on mass m the surface of earth in the ... A: Actually the formula should probably read: U=-GMm/R (not "times two") An object at a greater height ... | |
| mass and energy | 9/20/2008 |
| Q: how do you find the amount of energy produced by a moving object of known mass (weight?)? Thanks. ... A: When a ball of mass m falls a height h in the Earth's gravity field (with gravitational acceleration ... | |
| current - voltage - power - resistance | 9/19/2008 |
| Q: I want to ask that whether I is directly proportional to V(V=IR), or it is indirectly to P(power) ... A: You need to consider what context you dealing with, how the experiment is set up. The important ... | |
| I need help to prove my argument on sniping | 9/19/2008 |
| Q: So my friend and I were arguing over how sniping can all calculated with calculus, including factors ... A: Its all math, or physics (the math about nature). But the trouble is, to know all the variables ... | |
| mass and energy | 9/17/2008 |
| Q: how do you find the amount of energy produced by a moving object of known mass (weight?)? Thanks. ... A: If there is no opposing force to gravity, the velocity just keeps increasing. But in realistic ... | |
| LHC | 9/17/2008 |
| Q: I have read that the powerful magnets used will interfere with the Sun, Is this true and is it true ... A: The LHC has electromagnets that compensate the magnetic field of the Earth and any magnetic ... | |
| mass and energy | 9/17/2008 |
| Q: how do you find the amount of energy produced by a moving object of known mass (weight?)? Thanks. A: There is a well tested law in thermodynamics that is called the conservation of energy. It states ... | |
| Internal Energy | 9/15/2008 |
| Q: Could you help me solving a very simple physics related problem? I'm trying to figure out why ... A: The symbols used for physical variables are pretty much arbitrary, but fixed by convention - and ... | |
| Physics - Significant Digits | 9/14/2008 |
| Q: I don't understand the concept of Significant Digits. I can never remember how to tell the number ... A: Your question is very general. I suggest you read this article, which explains the concept of ... | |
| gravitation | 9/13/2008 |
| Q: sir few questions on gravitation 1) the gravitational force is inversly proportional to the ditance ... A: 1) You are absolutely right! As the masses come closer to each other, the gravitational force ... | |
| Translational Equilibrium | 9/12/2008 |
| Q: I am not to sure exactly what a translational eqiulibrium is. I am in the middle of an online lab, ... A: An equilibrium is a state in which all forces acting on a system cancel each other, so that the net ... | |
| Big Bang | 9/12/2008 |
| Q: if there was only emptiness before the big bang what banged thanks A: When scientists calculate the model of the development of the universe backwards, they find that not ... | |
| please help, im stuck | 9/10/2008 |
| Q: in a gas discharge tube containing hydrogen the electric current is carried partly by hydrogren ... A: Multiply the rate of electrons passing the point with the charge of the electron to arrive at the ... | |
| calculating mass density | 9/10/2008 |
| Q: I need a simple, generic explanation for calculating mass density. I have some different materials ... A: If you have the volume and the mass of an object, you can calculate its mass density simply by ... | |
| Helium (or hydrogen) and Density | 9/9/2008 |
| Q: I understand that a helium balloon floats because its density is less than that of the air's. But ... A: Hydrogen is too dangerous for application in a floatation device. It is so reactive, it combusts ... | |
| friction | 9/9/2008 |
| Q: sir we were doing this practical in physics of finding the coeeficient of static friction using an ... A: The coefficient of static friction, usually denoted by the greek letter mu, relates the tangential ... | |
| period and amplitude | 9/9/2008 |
| Q: I'm pre reading for a lab tomorrow and I'm trying to figure out the difference between period and ... A: Yes, the period goes on the x-axis of the graph. It is the distance between two consecutive maxima, ... | |
| Mechanics : Conservation of Linear Momentum | 9/6/2008 |
| Q: A kitten of mass 0.6 kg leaps at 30 degrees to the horizontal out of a toy truck of mass 1.2 kg ... A: If I understood the problem right, then the initial momentum is zero (stationary truck, stationary ... | |
| Mechanics: Projectile Motion | 9/6/2008 |
| Q: I did O Level Physics (up to Grade 10)...I just started A level physics this month and I cannot ... A: You did not solve your equation right. I get: u = 5m/s and thus s = 5m/s * 6s + 1/2 * 10m/s^2 * ... | |
| Shapes Of the trucks | 9/6/2008 |
| Q: Why are the tanks of the trucks containing liquids are oval shaped? A: All tanks or other containers holding liquids have roundish shapes (spheres, cylinders, oval ... | |
| strong nuclear force | 9/3/2008 |
| Q: can there be strong nuclear force between electron or is it only between nucleons? A: The strong force acts only between hadrons (the family of particles that the nucleons belong to) or ... | |
| Curious Physics Question about Paper | 9/2/2008 |
| Q: I fold a paper in half and prop it on a table forming a triangle, I then blow air through the ... A: I am not sure if I have understood your setup correctly. If not, please ask a follow-up question to ... | |
| science symbols? | 8/31/2008 |
| Q: im looking into higher science, and ive encountered a few symbols i have never seen before. like the ... A: Symbols can stand for different things in different contexts. There are no strict rules on what ... | |
| Negative Ions & Himalayan Rock Salt Lamps | 8/29/2008 |
| Q: I'm told that negative ions "fall" to the ground. Is this true? If so, if I set my rock salt lamp ... A: Some vendors of rock salt lamps claim health benefits from ions released by rock salt lamps. Their ... | |
| physics | 8/29/2008 |
| Q: we know that the wave lenght of violate colour of suns light is the l?owest.so the scattering of the ... A: the three different color receptors in the human eye have their maximum sensitivity at red, green ... | |
| Negative Ions & Himalayan Rock Salt Lamps | 8/29/2008 |
| Q: I'm told that negative ions "fall" to the ground. Is this true? If so, if I set my rock salt lamp ... A: The surface of the Earth has a negative electrical charge. But the charge density is very small so ... | |
| LHC | 8/27/2008 |
| Q: im pretty sure you know what the LHC or CERN im worried because in 2 weeks they will start it up and ... A: The scientists at CERN want to use the LHC to find out how our universe began and how it works at ... | |
| circular motion | 8/27/2008 |
| Q: why does the motorcycle rider in loop a loop death wall moving in vertical circle does not fall when ... A: the motorcycle rider in a wall of death is in a circular motion and thus experiences centrifugal ... | |
| Water flowing over distance through 6" pipe | 8/26/2008 |
| Q: Kevin, I'm considering installing a 6" pvc pipe from a free flowing ditch and running it straight ... A: As I wrote to you before this is outside my area of expertise, but since you implore me to take a ... | |
| Bouyancy and Density | 8/25/2008 |
| Q: I'll read it up. Two questions: -Do ice and water have the same density? -Why does a helium balloon ... A: -Do ice and water have the same density? Well, do ice cubes sink to the bottom, hover at constant ... | |
| Bouyancy | 8/25/2008 |
| Q: I know that the Bouyancy Force is equal to the weight(mg) of the fluid displaced by the object. My ... A: What the lecture means is that because of its large "hollow" parts (filled with air) a ship's total ... | |
| Bouyancy | 8/25/2008 |
| Q: I know that the Bouyancy Force is equal to the weight(mg) of the fluid displaced by the object. My ... A: I indeed formulated the answer in an ambiguous way. You are or course correct: The ship displaces ... | |
| Bouyancy | 8/24/2008 |
| Q: I know that the Bouyancy Force is equal to the weight(mg) of the fluid displaced by the object. My ... A: An iron rod displaces a volume of fluid equal to its volume. The weight of this displaced fluid ... | |
| how ship turns | 8/24/2008 |
| Q: How does a ship turn (Change direction) in water? and how they move in water !!!!!!! A: Ships use the principle of recoil for propulsion and steering. In order to accelerate a mass in a ... | |
| Earth's rotation | 8/24/2008 |
| Q: SIR WHICH FORCE IS RESPONSIBLE FOR THE ROTATION OF EARTH AROUND IT'S OWN AXIS AND HOW?AND WHAT WILL ... A: As a direct consequence from Newton's first law (the conservation of momentum) a free body in ... | |
| stabilty and torque | 8/21/2008 |
| Q: i want to ask 1) when we sit on bicycle or a two wheeler which is not parked on its stand, and our ... A: 1) When you ride your bicycle and it starts to tilt to one side, the bicycle conters this by ... | |
| maximum force at belt when car crash | 8/20/2008 |
| Q: i have 1 question but two condition.how to you calculate maximum impact force at the seat belt for ... A: Sorry, but I do not know any websites dealing with your question comprehensively. A brief treatment ... | |
| Thermophysics | 8/20/2008 |
| Q: The equation pV = rT is printed in the textbook without stating its origin. I am wondering if this ... A: the ideal gas equation pV = nRT can be derived empirically (from observations that led to precursors ... | |
| relativistic mass and rest mass | 8/19/2008 |
| Q: i was wondering what the evidence of actual mass is. because actual mass (rest mass) can not explain ... A: tha "actual" mass of an object is its relativistic mass. The rest mass is just that: the ... | |
| Gravity | 8/18/2008 |
| Q: What is gravity? A: this is a very general question, so let me refer you to this page for an answer: ... | |
| Eletricity | 8/17/2008 |
| Q: Which has greater resistance? A 100 watt bulb or a 60 watt bulb? A: Resistance R is related to voltage U and current I by R = U/I (or equivalently U=R*I (*)) Power ... | |
| accelrator for neutrons? | 8/16/2008 |
| Q: how we can accelerate neutron A: Neutrons are electrically neutral, so one cannot steer or accelerate neutrons, after they have been ... | |
| gravitation and centrifugal force | 8/13/2008 |
| Q: sir what will be the change in weight of a body if earth start revolving faster around sun and if it ... A: Yes. I already hinted towards that in my previous answer when I said that at the equator, where the ... | |
| gravitation and centrifugal force | 8/12/2008 |
| Q: sir what will be the change in weight of a body if earth start revolving faster around sun and if it ... A: There are two forces that need to be taken into consideration here: Gravity and centrifugal forces. ... | |
| electromagnetic waves | 8/11/2008 |
| Q: I have another question about electromagnetic waves. If all electromagnetic waves have frequency, ... A: The charged particles that change their energy state and thereby emit an electromagnetic wave can ... | |
| electromagnetic waves | 8/11/2008 |
| Q: If electromagnetic waves transfer electromagnetic energy, does this mean that everything, including ... A: I think you are confusing the electromagnetic field (of atoms, ..., everything) with electromagnetic ... | |
| physics | 8/11/2008 |
| Q: I'm wondering how it's possible that Chris Angel (see at youtube.com) can do what he does. all his ... A: As far as I know Chris Angel does not claim to do anything paranormal or supernatural. What he does ... | |
| Momentum and collision question | 8/9/2008 |
| Q: I hope you can help me find the proper simple equation that can help my students find the following ... A: for all three situations you need to solve the systame of equations given by 1) the conservation of ... | |
| physics newtons law | 8/7/2008 |
| Q: this is a really big pending debate between friends I hope you can resolve. I will not take a side ... A: There are no exceptions for Newton's laws: With every action comes a reaction. The Earth moves a ... | |
| circular motion | 8/4/2008 |
| Q: sir i want to ask when a stone tied to one end of a string and whirled around in the horizontal ... A: While the stone on the string does follow a circular path, the point where you are holding the ... | |
| mechanical advantage of simple machines | 7/26/2008 |
| Q: what's the difference between a mechanical advantage of a simple machine and velocity ratio of a ... A: The velocity ratio of a machine can be defined in different ways. For this answer I shall choose to ... | |
| Research review request--religion and science based | 6/27/2008 |
| Q: Greetings, My name is Larry Thomas and I am currently writing to you from Wiesbaden , Germany . I am ... A: I have perused your web site and found its topic to have nothing to do with science or physics. ... | |
| deadly dangers | 6/26/2008 |
| Q: nice to meet you! could a plane engine kill someone? how many nails from a nail gun could kill ... A: The engine of commercial airliner is certainly heavy enough to kill a person if dropped onto ... | |
| driving S-curves | 6/26/2008 |
| Q: I drive an S-curve going to work every day. I go up the first 1/2 of the "S" at 35 mph, I feel my ... A: What you are experiencing is probably part physics, part engineering and part psychology. Let me ... | |
| angular momentum | 6/25/2008 |
| Q: you said (about a moon receding from a planet and losing synchronicity): "I was describing two ... A: When the torque on the moon vanishes, from then on the angular momentum of the moon stays constant. ... | |
| angular momentum | 6/25/2008 |
| Q: I think I basically understand conservation of angular momentum. L=m*v(perpendicular)*radius. Am I ... A: I was describing two limit cases: 1) full tidal locking, synchronous orbit/rotation 2) no tidal ... | |
| Air pressure | 6/21/2008 |
| Q: A glass filled with water is covered by a piece of cardboard paper.When inverted the paper stays in ... A: The weight of the contents of the glass is not as important in this experiment than another fact: ... | |
| angular momentum | 6/19/2008 |
| Q: I think I basically understand conservation of angular momentum. L=m*v(perpendicular)*radius. Am I ... A: Rather than thinking about mass being lost (which is not the case as you correctly state) one should ... | |
| angular momentum | 6/18/2008 |
| Q: I think I basically understand conservation of angular momentum. L=m*v(perpendicular)*radius. Am I ... A: It is not clear to me what you mean by "synchronous". Please clarify this point in order for me to ... | |
| Physics | 6/14/2008 |
| Q: I have got two questions which are kind of related and I would be glad if you could satisfy my ... A: You are right, the surface of the liquid in a water or fuel truck is horizontal as long as the truck ... | |
| forces | 6/12/2008 |
| Q: suppose a box is lying on a table . we push it. when we push it we exert some force on it and at the ... A: The person you asked was right, the forces are acting on two different bodies: The pushing force is ... | |
| Physics | 6/10/2008 |
| Q: I have heard that everything has electromagnetic energy, even the smallest particles. I was ... A: Not every elementary particle has an electric charge. Those particles without electric charge (e.g. ... | |
| Interference of Waves | 6/4/2008 |
| Q: I have yet to find a satisfactory answer and all questions I've found move towards more complicated ... A: When two waves (or wave packages) meet at one point in a way that they cause destructive ... | |
| anti particles of neutral particles | 6/2/2008 |
| Q: helo sir, i am a student of physics doing M.Sc physics from kashmir university ... A: You are right: The definition of an antiparticle having the same mass as the corresponding particle, ... | |
| Physics of swing motion | 5/28/2008 |
| Q: Here is a question that has puzzled me for a long time. How does a person on a swing start moving ... A: Newton's laws can be applied to rotating bodies as well. After all these laws were inspired by ... | |
| Time Travel | 5/24/2008 |
| Q: Has anyone yet disproved Einstein's idea that if anything were to pass the speed of light it would ... A: No one has conducted a sucessful experiment in which something travelled faster than the speed of ... | |
| movement and force | 5/21/2008 |
| Q: I'm a grade 11 physics student, that is horrible in physics. i have 2 questions to ask, 1. why can't ... A: in my previous answer I simplified the case a bit and neglected elasticity and fragility. Of course ... | |
| movement and force | 5/20/2008 |
| Q: I'm a grade 11 physics student, that is horrible in physics. i have 2 questions to ask, 1. why can't ... A: 1. People have mass. So it would take infinite energy to accelerate them to the speed of light. For ... | |
| Quantum Mechanics - Many Worlds | 5/19/2008 |
| Q: I am very curious about the Many Worlds Interpretation of Quantum Mechanics. Are the dimensions ... A: The dimensions in every one of the many worlds are three space dimensions plus one time dimension ... | |
| Kinetic Energy with Impact | 5/16/2008 |
| Q: Firstly, thank you for taking the time in answering this question. I'm a software developer at ... A: you wrote: "should a car hit a very large object at 100km/h that the forces involved are then ... | |
| Sound | 5/14/2008 |
| Q: my knowledge level of physics is that of a curious bystander although I have 2 degrees in biomedical ... A: Sound is not such a complicated phenomenon when you reduce it to what it is on a scientific level: ... | |
| I find we CAN jump further from west to east. Why? | 5/11/2008 |
| Q: We knew from our high school teachers that we may jump for the same distance whether we jump from ... A: Your reasoning is perfecly right, there is a theoretical basis for your conclusion. But if you ... | |
| Particle Physics | 5/10/2008 |
| Q: The Large Hardon Collider team feel there is a minute chance that micro black holes might be created ... A: a black hole has a finite volume (which expands with increasing mass) and a finite mass (as much ... | |
| Gravity | 5/6/2008 |
| Q: Why doesn't the earth's gravity pull all the clouds to the ground? A: Since humid air is lighter than dry air, humid air rises up in the atmosphere until it reaches an ... | |
| Combined probabilities | 5/1/2008 |
| Q: I have made up an example of the problem, although feel free to make your own example... 1. I have ... A: 1) If the probabilities of filter A are the same whether filter A is applied to the whole lot or ... | |
| Combined probabilities | 4/28/2008 |
| Q: I have made up an example of the problem, although feel free to make your own example... 1. I have ... A: Yes that is correct as long as your filters test independent properties. If you test for dependent ... | |
| Combined probabilities | 4/26/2008 |
| Q: I have made up an example of the problem, although feel free to make your own example... 1. I have ... A: If I may assume that condition 2 and 3 are independent, then the probability of drawing a random ... | |
| physics | 4/21/2008 |
| Q: hypothetically what would happen if all the atoms in an object suddenly stopped moving? A: The random movements of atoms about their equilibrium position in the atomic lattice of a solid body ... | |
| force | 4/16/2008 |
| Q: Sir These are questions related to force 1) Any body falling under gravity accelerates with the ... A: 1) The acceleration of a free falling object is determined only by the strength of the gravity ... | |
| Diffusion & Advection & Dispersion | 4/15/2008 |
| Q: Could you explain me what is the difference between Diffusion, Advection and Dispersion. I'm doing ... A: I could not define the terms better than wikipedia does, so I will just refer you to the relevant ... | |
| fundamental forces | 4/11/2008 |
| Q: i knew there were five fundmental forces electricity, magnetism, strong nuclear force , weak nuclear ... A: The electric and magnetic forces have been unified in the middle of the 19th century, most notably ... | |
| Schrodinger question | 4/10/2008 |
| Q: I majored at uni in physics and pure maths years ago so I'm hoping you can help. I assume ... A: this is exactly the question the Schroedinger equation answers. Its solution gives you the time ... | |
| force | 3/31/2008 |
| Q: sir A rocket is moving with constant speed in space by burning fuel and ejecting out burnt gases ... A: As you state correcctly, when the rocket ejects gas, its mass decreases. But since the gas is ... | |
| what causes electrical charge? | 3/29/2008 |
| Q: What gives subatomic particles their positive and negative charges? Can the charge be changed? Is ... A: Charge, like mass, is just an intrinsic property of some elementary particles. Since elementary ... | |
| Physics | 3/27/2008 |
| Q: Sir, I am an asian student studying in a grade equicalent to grade 10 in the U.S. I have been ... A: In every collision there are two masses that collide. Their total momentum is conserved, i.e. if one ... | |
| Physics | 3/27/2008 |
| Q: Sir, I am an asian student studying in a grade equicalent to grade 10 in the U.S. I have been ... A: Momentum (p) is always conserved, even in inelastic collisions. Let's take for example the ... | |
| spinning and magnetism | 3/26/2008 |
| Q: I am having a hard time understanding this conceptually. If I have a sphere with a surface charge ... A: Static electric charges create an electric field. Only as electric charges are moved do they create ... | |
| Light waves | 3/25/2008 |
| Q: I understand that light is both a particle and a wave. Why does light travel in waves that have up ... A: The minima and maxima of the electromagnetic field are not minima/maxima of the energy! You know ... | |
| glass harmonica and standing waves | 3/25/2008 |
| Q: I am a PhD in a technical area, but it's been decades since I spent time thinking about basic ... A: The standing wave in a pipe is actually in the air - the surrounding material only vibrates in ... | |
| granular solids | 3/24/2008 |
| Q: I cannot seem to find the answer of why a solid object will "float" on a granular solid when shaken. ... A: this and similar phenomena are known in the granular matter community as the "Brazil nut effect". ... | |
| Ice Crystals | 3/24/2008 |
| Q: This is mywhy is in the middle of ice, white ? (have you noticed ?) I guess the reason must be ... A: You are right: The white, opaque parts of ice are parts where there is no perfect crystal structure. ... | |
| force | 3/23/2008 |
| Q: sir few questions on force and force of gravity 1) Why does inertia of an object depend on mass ... A: 1) The inertia of the two bodies is equal, but the faster body has more momentum! Inertia and ... | |
| measuring absolute speed | 3/22/2008 |
| Q: I asked this question earlier to Azhar Ali Haidry, and HAL (other experts) but they didn't answer ... A: The matter is a bit more complicated as Einstein showed in his theory of special reletivity. He ... | |
| Electric Fields and Potential | 3/21/2008 |
| Q: I have taken E&M and used Griffiths. In class we learned how to calculate Electric Field and ... A: To calculate the electric field of a given charge distribution you need to evaluate the volume ... | |
| Light waves | 3/21/2008 |
| Q: I understand that light is both a particle and a wave. Why does light travel in waves that have up ... A: Light really travels in a straight line. The amplitudes are not "wiggly paths" that the light ... | |
| Laser Projector | 3/18/2008 |
| Q: I was wondering if there is any such thing as a movie type projector that uses laser light, or if ... A: Laser effects like in discos or at rock concerts are fairly easy to create, you just need a laser ... | |
| electric field | 2/16/2008 |
| Q: i want you to explain to me how am going to slove this problem. A charge of about 5mc is placed at ... A: you need to use Coulomb's Law ( http://en.wikipedia.org/wiki/Electric_field#Coulomb.27s_law ) to ... | |
| What exactly are "flames"? | 2/16/2008 |
| Q: What exactly are "flames"? From what I've read about, it's where atoms are rearranging, with a net ... A: Usually the fuel and oxygen do not spontaneously react chemically - they need an activation energy ... | |
| Molecular Mass | 11/8/2007 |
| Q: I am reviewing a section on molecular mass and do not really understand it. Can you explain how I ... A: The numbers mean that a molecule of aspartame is made of 14 carbon atoms, 8 hydrogen atoms, 2 ... | |
| effect of rotation of earth | 11/8/2007 |
| Q: Sir,we've learnt in dynamics that due to the rotation of the earth one bank of a river is higher ... A: Since on Earth we are moving on the surface of a rotating sphere, there is - in our frame of ... | |
| Problems with no air resistance | 10/27/2007 |
| Q: How can I solve a problem when it is asking me how high my object would go if no air resistance ... A: If you know the initial velocity, then you can use the formula for the free fall (with initial ... | |
| Radioactive decay chain | 10/18/2007 |
| Q: General alpha decay of a nuclei follows the rule that the atomic number decreases by 2 and mass ... A: The decay chain of U-238 to Pb-206 (called the "radium chain") is a succession of alpha and beta ... | |
| Friction | 10/16/2007 |
| Q: I am in 12th grade. I don't get why the reason why a car stuck in snow cannot move, is because there ... A: Under good road conditions friction impedes sliding of the tires on the road. At the contact point ... | |
| Quantum mechanics | 10/11/2007 |
| Q: So my question is what happens to if the momentum operator contains no imagenary component, so its ... A: The wavefunction in the momentum space is the Fourier transform of the wave function in position ... | |
| physics | 10/8/2007 |
| Q: which has more momentum a 20kg truck or a 20000kg truck?? i am not very smart at science please ... A: Momentum is mass times velocity. So in order to decide which truck has more momentum you need to ... | |
| Motion- Physics | 9/19/2007 |
| Q: A woman of mass (m) clings to a rope laddar suspended below a balloon of mass (M). The balloon is ... A: This sounds like a homework question, so I will only guide your intuition a bit with a hint: There ... | |
| Gas density in outer space | 9/18/2007 |
| Q: What is a 'ball-park figure' for the density of gas in 'outer' space? A: Outer space contains such sparse matter that it can be effectively thought of as a vacuum. The ... | |
| force | 9/15/2007 |
| Q: how much force i have to apply when i climb a staircase? my mass is 45Kg. when i climb a staircase i ... A: First you lift your leg to one step higher, but then you push up your entire body until you are ... | |
| fuse | 9/15/2007 |
| Q: i have a question regarding the electric fuse. An electric currentof rating 3Kw,250V.I want to know ... A: Power P is voltage V times current I: P=V*I Solving this for the current gives: I=P/V A device ... | |
| force | 9/10/2007 |
| Q: How would you calculate the forward force if you have a mass, speed and time A: Newton's second law states that force is mass times acceleration: F = m * a So to calculate the ... | |
| tachyons and E=mc2 | 9/9/2007 |
| Q: Are there objects or particles that in fact move faster than the speed of light, and how do they ... A: particles that move faster than the speed of light have not been detected (yet?). But there are ... | |
| Total speed of impact on car crash | 9/7/2007 |
| Q: Would you be able to explain what happens when 2 cars collide head on when both cars are driving 60 ... A: If the two cars are identical, i.e. they have the same speed, the same mass and are of the same ... | |
| ferrous | 9/6/2007 |
| Q: my question is either a hard one or realy easy. I've been wondering about the nature of the n clouds ... A: What do you mean by "infered magnetism"? Perhaps "induced magnetism"? ... | |
| Miniture motor torque | 8/28/2007 |
| Q: I'm trying to figure out the torque I need for a motor. The motors I have seen all give the torque ... A: If each revolution of the motor lifts the balls up 30mm, then this is the circumference of the ... | |
| waves | 8/28/2007 |
| Q: Just wanted a brief explanation on what happens to the relative magnitude of waves as frequency is ... A: the frequency and the amplitude of a wave can be varied independently from each other. So the ... | |
| Physics | 8/27/2007 |
| Q: what are two examples of tasks for which each kind of magnet would be more suitable? A: I suspect this question is a homework assignment. I do not give complete solutions, but perhaps I ... | |
| Time Travel | 8/25/2007 |
| Q: I know this is probably one of the more popular questions to ask, but is time travel in general, and ... A: Time travel utilized by humans is stuff from science fiction. Although there are some effects ... | |
| Bubbles | 8/23/2007 |
| Q: what gases are in the small bubbles that form when we begin to warm water? A: In liquid water all kinds of gasses can be dissolved. In surface water (rivers, lakes, oceans) there ... | |
| pressure | 8/21/2007 |
| Q: sir i want to ask few questions on water pressure 1) why does water seeks its own level? 2) In a ... A: 1) Water (like all mass) is subject to gravity. So a body of water will tend to move downward, and ... | |
| Selective Perception | 8/18/2007 |
| Q: how are you going? My name is Christina and I live in Australia. Thank you for taking the time to ... A: There is no physical (let alone quantum physical) reason for you or anyone else noticing the time ... | |
| Neutrons to Protons & vice versa | 8/16/2007 |
| Q: Reference Book: "Cosmic Landscape" by Leonard Susskind (Dec 2005) Knowledge Level: avid reader of ... A: I am sorry to read your quite harsh ratings on my answer. Your confusion seems to stem from the ... | |
| electric shock | 8/16/2007 |
| Q: 1) when a metallic body of a appliance comes in contact with live wire why does it acquire the ... A: 1) If you attach a second wire to a live wire, it acquires the potential of the live wire, since it ... | |
| gravity why is it so weak | 8/15/2007 |
| Q: I was wondering why is gravity such a weak force? thank you A: the reason for the relative strengths of the four fundamental interactions of matter - strong ... | |
| Quantum Mechanics | 8/15/2007 |
| Q: Firstly thankyou so much for volunteering! I really appreciate it.. The service you provide is very ... A: A complete solution would be too long to type here, so please see these pages for some insight into ... | |
| Busting gluons -- my ultimate high-energy physics fantasy | 8/14/2007 |
| Q: Theoretical situation: It is 12:00 AM on a dark moonless, cloudless night in the desert. I am here ... A: The air molecules are composed of atoms, the nuclei of which are composed of protons and neutrons, ... | |
| ohm's law experiment | 8/9/2007 |
| Q: I am 13 and would like to preform an experiment that would demonstrate ohm's law could you please ... A: read about Ohm's law here: http://en.wikipedia.org/wiki/Ohm's_law (just skip the "Physics" section ... | |
| power distribution | 8/9/2007 |
| Q: sir i have two doubts 1) power from power station in suppose 11kV. let the electricity produced 1MW. ... A: You are right. If indeed the power station produces 1MW and the total current used by heavy industry ... | |
| Kettles | 8/7/2007 |
| Q: Can a kettle work with batteries. In other words, do you find an element which you can use in a ... A: Oh, sorry, I seem to have created a misunderstanding. What I meant is that in practice it is not ... | |
| Kettles | 8/6/2007 |
| Q: Can a kettle work with batteries. In other words, do you find an element which you can use in a ... A: An electric kettle uses an electric power to heat water. Since batteries are a source of electric ... | |
| electricity | 8/6/2007 |
| Q: i know u must be really pestered by me, but where should i clear my doubts. so i keep on asking ... A: let me tackle the questions contained in a structured way: In an electric circuit we have a voltage ... | |
| size of particles traveling speed of light | 8/4/2007 |
| Q: What would happen to the size of an item if it was able to travel the speed of light? Would it ... A: The effect you are referring to, the length contraction at relativistic speeds, is called "Lorentz ... | |
| electricity | 8/4/2007 |
| Q: why does current flowing through a conductor produce heat ain it. I know that heat produced is ... A: sorry for the long wait, but the servers at AllExperts seem to have been overloaded. I could not get ... | |
| electricity | 8/2/2007 |
| Q: why does current flowing through a conductor produce heat ain it. I know that heat produced is ... A: the process that produces heat in a conductor is also the reason the conductor has resistance: ... | |
| moutain bike physics. | 7/27/2007 |
| Q: i have been having a long debate with friends about mountain bikes. its a simple question. are ... A: All kinds of bikes are more efficient on flat, hard suraces (e.g. concrete) than on bumpy roads or ... | |
| internal resistance | 7/24/2007 |
| Q: 1)why does the internal resistance of a battery is less if the surface area of the electrodes is ... A: Katrina. All of the physical and chemical processes inside the battery contribute to the internal ... | |
| internal resistance | 7/23/2007 |
| Q: 1)why does the internal resistance of a battery is less if the surface area of the electrodes is ... A: Batteries produce electric energy from a chemical reaction (which frees electrones at the negative ... | |
| potential | 7/18/2007 |
| Q: helo sir 1) I was reading the chapter on electric potential. Now the elctric potential in all books ... A: 1) You say "positive charge cannot move". You are probably confusing the situation in a metallic ... | |
| elementary particles | 7/16/2007 |
| Q: Do elementary particles "decay" or undergo any transitions of any kind (eg, like the quantized ... A: Elementary particles have no internal degrees of freedom, they can only change their energy in ... | |
| neutron composition | 6/24/2007 |
| Q: I have been reading a geology text in which it states that a neutron is actually a proton and ... A: Your original impression is right: Neutrons are composed of one up quark and two down quarks. Since ... | |
| physics help please | 6/24/2007 |
| Q: I have a problem and they have set up a table for us. It shows the mass of an object, the initial ... A: The "C" is the specific heat capacity. It is the energy (in J) needed to make 1 kg of the material ... | |
| electrical circuits | 6/21/2007 |
| Q: .. i have a few question(s) if there is a electrical circuit consisting of a battery, globe (X), an ... A: If the removal of the globe leaves the circuit open, then there is no current and the Ampere-meter ... | |
| beta particle, electromagnetic shielding | 6/12/2007 |
| Q: What is the difference between electron and beta particle? Why some electrical devices like TV and ... A: A beta particle is actually an electron, but the name "beta particle" specifies an electron that was ... | |
| velocity | 6/8/2007 |
| Q: Can you give an example of a body with zero velocity but with constant acceleration? A: If you hold an object and then suddenly let it go, then its acceleration is g = 9.81 m/s^2 (Earth's ... | |
| work and efficiency | 6/5/2007 |
| Q: Please help, myWhat is the effiency of a pulley system that will raise a 2000-N load a vertical ... A: I don't do homework solutions, but perhaps two hints are all you need: 1) Efficiency is the ratio ... | |
| bouyancy | 6/3/2007 |
| Q: theoretically, if I have a boat that weighs 2,000 pounds, how many cubic feet of air would it take ... A: Archimedes' principle states that the buoyant force on an object is equal to the weight of the water ... | |
| Rotation on objects. | 6/1/2007 |
| Q: Johnson, I am a high school student, and I am curious about putting spin on thrown/launched ... A: The application of Bernoulli's principle on the path of rotating projectiles is called the Magnus ... | |
| buoyancy | 5/26/2007 |
| Q: i am designing a inflatable flotation aid for kitesurfers. Using a 10gram CO2 cylinder with a volume ... A: The pressure of the bladder is not directly related to the buoyancy, but its volume is. The buoyant ... | |
| physics | 5/25/2007 |
| Q: how aquatic animals and plants survive in extreme cold weather? A: This is a good question, since at temperatures below 0°C water freezes, including water inside the ... | |
| Physics - Motion and Energy | 5/20/2007 |
| Q: Our college professor gave us the following question (paraphrased): Suppose a car (2000kg) moving ... A: M., The car loses potential energy (mgh) during the jump (since it is at a lesser height at the ... | |
| Physics - Motion and Energy | 5/19/2007 |
| Q: Our college professor gave us the following question (paraphrased): Suppose a car (2000kg) moving ... A: M., I don't see why you should need the conservation of energy here. You just need the initial ... | |
| bullet distance | 5/12/2007 |
| Q: If a man fired a bullet from a handgun in a perfectly upward direction, how far would the bullet ... A: Gravity takes hold immediately and thus decelerates the bullet at a rate of g=-9.81 m/s^2 (the ... | |
| Cell phones | 5/9/2007 |
| Q: When I receive a text message to my cell phone does it get heavier or lighter or stay the same? A: A text message is received in digital form, carried by electromagnetic waves (like radio waves) and ... | |
| measurement, circular motion | 5/7/2007 |
| Q: what is the difference between a chemical balance and physical balance? when a bucket full of water ... A: Physical balance is a state where all forces acting on a system cancel each other and so there is no ... | |
| ASYMPTOTIC FREEDOM | 5/4/2007 |
| Q: it is said that quark particle are binded together by strong ( or colour ) force but as they come ... A: With elementary particles our everyday intuitive thinking does not work any more. Quarks are thought ... | |
| length contraction and mass variation(special relativity) | 4/30/2007 |
| Q: please expalain length contraction and mass variation in special theroy of relativity with simple ... A: Length contraction (sometimes also called Lorentz contraction) is the effect that lenghts and ... | |
| inertia, impact | 4/29/2007 |
| Q: why a man falls on cemented floor is hurt seriously then fall on kachcha (soft mud floor)floor? A: A cement floor does not deform upon impact, so the only way to dissipate the kinetic energy ... | |
| what boils faster | 4/23/2007 |
| Q: what boils faster hot, cold, room temp water? also, what freezes faster- hot, cold room temp water? ... A: To raise the temperature of a water from an initial temperature T1 to a final temperature T2 you ... | |
| elastic and inelastic collisions | 4/23/2007 |
| Q: Kevin, I am having trouble in finding final velocities in elastic and inelastic collision problems. ... A: For these kinds of problems you always use the conservation of momentum and the conservation of ... | |
| physics | 4/22/2007 |
| Q: There is an amusement park ride where the riders spin in circle and "stick" to the wall when the ... A: The centripetal force is the force that forces the passengers on their circular motion. It is the ... | |
| physics | 4/22/2007 |
| Q: If an amusement park ride goes in a constant circle (then the floor drops) does it have a constant ... A: The motion of this amusement park ride is a circular motion. Read about the physics of circular ... | |
| surface tension | 4/19/2007 |
| Q: m 16 years old I really don't understand the concept of surface tension. I tried to find the answer ... A: Water molecules attract each other - this force is called cohesion. So they have the tendency to ... | |
| tension | 4/18/2007 |
| Q: I hav a doubt In single fixed pulley If there is a load of 100N on one side of the rope passing over ... A: The friction is an additional force on the rope at the pulley, of magnitude 10N and in direction ... | |
| science-weight and power | 4/18/2007 |
| Q: Two identical cars with the same weight are both traveling down the road. One is moving at 50 m/s ... A: Your question sounds like a homework problem. I never give homework solutions, but I can give you ... | |
| force of impact (kinetic energy?) | 4/16/2007 |
| Q: If you would, please tell me (or advise me how to calculate bearing in mind I'm an idiot)the force ... A: Force F is mass m times acceleration a. F = m * a Acceleration is change of velocity dv (= v_final ... | |
| gas physics question | 4/14/2007 |
| Q: I am a undergraduate at Rutgers UNiversity and heaving tremendous problem with this physics ... A: I never give homework solutions, but perhaps some hints will help you even better: (a) What is the ... | |
| Momentum | 4/12/2007 |
| Q: I need your help please with the followingA .15 kg frame, when suspended from a coil spring, ... A: I don't give homework solutions, but I believe some hints should help you solve the problem ... | |
| friction | 4/12/2007 |
| Q: frictional force acts to oppose one surface from sliding relative to the other with which it is in ... A: The wheel does not stick to the road like it is glued to it. The contact point changes continuously ... | |
| friction | 4/10/2007 |
| Q: frictional force acts to oppose one surface from sliding relative to the other with which it is in ... A: You have to distinguish between different types of friction: - sliding friction - rolling friction ... | |
| Sound/Intensity | 4/10/2007 |
| Q: I am working on a question from a past AP Physics B Test - (I am studying for the exam in May!) The ... A: Your problem deals with interference. Have a look at this page: ... | |
| momentum | 4/9/2007 |
| Q: A rocket moving with costant speed in space by burning fuel and ejecting out the burnt gases through ... A: The question says that the rocket is moving at constant velocity v. It is shedding fuel by burning ... | |
| brownian motion | 4/4/2007 |
| Q: helo mr kevin i want to ask questions related to brownian motion 1) why does brownian motion of the ... A: 1) Larger particles in most cases also means more massive particles, and since a transfer of the ... | |
| Sound vision | 4/4/2007 |
| Q: I was wondering if to your knowledge it is possible to aim a device that creates high sound ... A: Sound waves are reflected by any solid surface and are thus not suitable for such a secret device. ... | |
| Energy and force | 4/3/2007 |
| Q: I just confuse about energy and force. The bottle filled with 100cc water was drop at 1 meter height ... A: Sorry I forgot that point. You are right, the force is perpendicular to the surface and thus only ... | |
| Energy and force | 4/2/2007 |
| Q: I just confuse about energy and force. The bottle filled with 100cc water was drop at 1 meter height ... A: You are right about the energy. The potential energy E=mgh gets converted into the same amount of ... | |
| force | 3/29/2007 |
| Q: I know that you do not give solution to numericals. But i m stuck in one problem . Can you just give ... A: You are right about the gravitational force exerted by the Earth on the ball, and that this is the ... | |
| force | 3/28/2007 |
| Q: I know that you do not give solution to numericals. But i m stuck in one problem . Can you just give ... A: Force is momentum change per time. The time interval is given, so all you need is the change of ... | |
| Kinetic theory | 3/27/2007 |
| Q: The Kinetic Theory of Matter is based upon the assumption that all matter is made of molecules and ... A: The kinetic theory applies mostly to gasses (and to some extent to liquids). It explains ... | |
| conservation of momentum | 3/27/2007 |
| Q: An 80 kg astronaut carrying a 20 kg tool kit is initially drifting toward a stationary space shuttle ... A: I don't do homework solutions, but perhaps some hints will help you solve the problem by yourself. ... | |
| please settle a brotherly diagreement | 3/26/2007 |
| Q: Not sure if I'm even in the correct area but here's the question/issue. I have a large double window ... A: You are partially right, but your analogy does not quite work, since it does not take into account ... | |
| Simple Harmonic Motion | 3/26/2007 |
| Q: What is Simple Harmonic Motion in laymens terms? I need to explain it to a pack of middle schoolers ... A: check this page and see what you can use for your class. ... | |
| Net Force | 3/25/2007 |
| Q: A small plane climbs with a constant velocity of 250 m/s at an angle of 28 degrees with respect to ... A: The plane is moving at a constant velocity, so there is no acceleration. Now since every force F ... | |
| force | 3/21/2007 |
| Q: If a truck and a car moving with same velocity towards each other collide with each other with each ... A: according to Newton's third law, every force generates an opposing force of equal magnitude in the ... | |
| explanation plzz | 3/20/2007 |
| Q: im havin alittle problem im needing help with. i hope you can help me. 1. A car with an initial ... A: 1. Deceleration of 0.5 m/s^2 means a reduction of the velocity of 0.5 m/s per second (0.5 m/s^2 = ... | |
| weightlessness | 3/19/2007 |
| Q: john again Can u explain why do we feel weightlessness when we are inside a freely falling lift? A: you actually never feel your weight. What you feel is the equal supporting force the ground exerts ... | |
| gravity | 3/19/2007 |
| Q: this is the follow up of the question which i asked earlier that why value of acceleration due to ... A: 1) Yes, you can view this as there being two centers of gravity. The effective force on you is the ... | |
| fuse | 3/19/2007 |
| Q: an electric kettle is rated 3kW,250V. so its current carrying capacity is 12A. can it be used in a ... A: The circuit fuse is there to protect the circuit (the wires in the wall) from overheating. It is not ... | |
| FORCE | 3/18/2007 |
| Q: I m 17 years old and studyin in XI standard(Sciene). My question is when we lift an object we do ... A: in order to lift a mass you need to apply its weight as the lifting force. Of course you actually ... | |
| Mirrors & Lenses | 3/16/2007 |
| Q: If a concave mirror is used to reflect light from an object that is placed farther from the mirror ... A: such an image is called a virtual image. Read more about it here: ... | |
| simple harmonic motion | 3/14/2007 |
| Q: sir can u tell me in the case of an oscilating pendulum what is the work done by the tension in the ... A: You did not enter any text in your follow-up question. In case you want more clarification on the ... | |
| simple harmonic motion | 3/13/2007 |
| Q: sir can u tell me in the case of an oscilating pendulum what is the work done by the tension in the ... A: The forces acting on a pendulum of mass m are 1) gravity (always downwards) Fg = m*g (g = 9.81 ... | |
| amusement park ride | 3/13/2007 |
| Q: I am reviewing for my exam and I need help understanding this problem. I already solved it and got ... A: Gravity is Fg = m * g - this is the tangential force on the surface (backplate of the ride)(g=9.81 ... | |
| Newton's third law | 3/12/2007 |
| Q: this is regarding Newton's third law. When we are standing or sitting on ground, our weight is ... A: There are four forces involved here: Forces acting on the person: (1) Earth's gravity (downwards) ... | |
| mass energy equation | 3/12/2007 |
| Q: before u read the questions i apologise for asking so many detailed questions. bUt please do reply.I ... A: 1) Unfortunately, the best examples for this are all from the area of nuclear reactions. Total ... | |
| acceleration due to gravity | 3/12/2007 |
| Q: Why is the value of acceleration due to gravity(g) more at the poles than at equators? Why does the ... A: The force of gravity is the same at the poles and the equator, but at the equator you are travelling ... | |
| physics | 3/10/2007 |
| Q: I have tried to draw a diagram of a rope (/\)passing over a pulley (o). On one side of pulley a ... A: Tension (at any given point of a rope) is a force pair: the force the left side of the rope exerts ... | |
| physics of tug-of-war | 3/10/2007 |
| Q: Consider a tug of war between two people who pull in opposite directions on the ends of a rope. By ... A: It's all in the legs ;-) If the force that the legs of B exert on the ground is larger than the ... | |
| Natural Frequency | 3/9/2007 |
| Q: If I pluck a guitar string do I hear JUST the natural frequency or do I hear the natural frequency ... A: In fact all the harmonics are present, but your ear (or to be more precise: your brain) tunes in to ... | |
| physics | 3/9/2007 |
| Q: 1.IF a block is pushed , it doesn,t move because of the friction(static friction). SO is friction ... A: 1. Yes. 2. The forces acting on the boy are the reaction force from the block and the (his shoes) ... | |
| physics | 3/8/2007 |
| Q: This question is regarding the string tension in pulleys 1) What is exactly tension in a string? ... A: 1) Tension is a reaction force applied by a stretched string (rope or a similar object) on the ... | |
| physics | 3/8/2007 |
| Q: please answer the following questions related to simple machine 1. how does friction reduce the ... A: 1. Friction dissipates energy, i.e. it turns "useful" energy (e.g. motion) into "wasted" energy ... | |
| relativistic mass increase | 3/7/2007 |
| Q: you said since velocity can not be increased, hence mass increases. agreed. But mass means amount of ... A: There is no extra matter added. A single atom is more massive when it is accelerated to relativistic ... | |
| relativistic mass increase | 3/5/2007 |
| Q: why does an object on mass m gains mass when it travels with the speed of light? I know it is ... A: The relativistic mass increase is real (not just an assumption) and is proven in each run of a ... | |
| physics | 3/3/2007 |
| Q: when a body is rolled up on an inclined plane, how come the force aplied is in horizontal direction? ... A: Both ways of applying the force are possible. If the force is applied in horizontal direction, then ... | |
| physics | 3/3/2007 |
| Q: I don't know much about Physics, but the other day I saw this really cool experiment and I wanted to ... A: The center of mass of the two-fork constuction lies directly below the point of support (that is the ... | |
| space-time warping/curvature | 3/2/2007 |
| Q: i studied some the derivations and calculations about space time when i was in school,but to me they ... A: The tarpaulin example is just a way to visualize what space-time warping could look like. One ... | |
| Physics in the car | 3/2/2007 |
| Q: I am wondering how Newton's three laws apply to the car? Thank you so much, Ash A: Newton's laws can be stated like this: First Law If no external force acts on a particle, then it ... | |
| Astronomy | 2/27/2007 |
| Q: I just don't know how to set up the equations or where the numbers come from 1. Normal ... A: Sorry, I do not give homework solutions, since they are YOUR homework (and not mine) for a very good ... | |
| physics | 2/27/2007 |
| Q: This is regading my second question. you said that the only force acting on the ball is force due to ... A: In the horizontal direction there is no force acting on the ball, so in this direction it ... | |
| physics | 2/25/2007 |
| Q: please explain why does a ball thrown vertically upwards by a person in a moving train comes back to ... A: While the train is moving at a constant velocity there are no forces acting on the passengers and ... | |
| physics | 2/25/2007 |
| Q: can u answer me why when a corridor train suddenly starts, the sliding doors of some compartments ... A: Newton's first law states that without external forces bodies in motion stay in motion on a straight ... | |
| Tea & Coffee (Temperature) | 2/21/2007 |
| Q: Can you please explain what everyone asks, but, no one knows... Why is a cup of tea, hotter ... A: There is no physical reason why a cup of tea should be hotter than a cup of coffee. The reason might ... | |
| physics | 2/21/2007 |
| Q: This was the question asked in Icse Class X board exam Physics paper(India). A swimmer diving in a ... A: A swimmer diving into a shallow water tank gets hurt, because he hits the ground (a solid). A ... | |
| physics | 2/19/2007 |
| Q: good to know u r back. can u explain me why a magnetic field is resolved into its horizontal ... A: As you know, electromagnetic fields are vector fields, so they have three components. In a cartesian ... | |
| How do I create a strong electromagnet? | 2/18/2007 |
| Q: When I was at school learning about electromagnets, I was wondering this, how do I create a strong ... A: The strength of an electromagnet can be increased by several methods: - a higher electric current - ... | |
| physics/synchronized pendulums | 2/12/2007 |
| Q: Why do pendulums synchroize? A: check this page for a brief description of the phenomenon and the reference given for a detailed ... | |
| physics | 2/11/2007 |
| Q: The velocity of a wave is given as square root of (E/d)where E is the elasiticity of the medium and ... A: The reason that sound travels faster in solids than in gas is that solids have a higher stiffness ... | |
| Astronomy | 2/10/2007 |
| Q: I am trying to figure out, given that the distance from Earth to the Sun is 150,000,000 km, through ... A: If you approximate the Earth's orbit around the sun as a circle with 150 000 000 km radius (r), then ... | |
| Science Project experiment - density | 2/9/2007 |
| Q: My Son is doing a science experiment about density. The experiment goes as follows: 1)Fill an ... A: The law governing buoyancy - and relating it to density - is called "Archimedes' principle", as it ... | |
| physics | 2/7/2007 |
| Q: does the mass of an atom depend on its size? is it necessary that atoms bigger in size have more ... A: The mass of an atom depends on the number of protons and neutrons in its nucleus. The size of an ... | |
| physics | 2/7/2007 |
| Q: The velocity of a wave is given as ?ăE/?ăd where E = elasticity of the medium and d is density of ... A: The transmission of sound can be explained using a toy model consisting of an array of balls ... | |
| physics | 2/6/2007 |
| Q: why are the magnetic poles situated slightly inside and not exactly at the ends of a magnet? A: A magnet is a substance where all atoms are aligned (more or less) in the same direction. North ... | |
| physics | 2/6/2007 |
| Q: can u explain me the concept of potential and potential difference in a simplified manner since i m ... A: Electric potential is the potential energy per unit of charge associated with a static ... | |
| physics | 2/5/2007 |
| Q: why cant be static electricity developed in conductors? Why it always developed by rubbing two non ... A: Static electricity is produced when two substances are first in contact, thus enabling electrons to ... | |
| very simple question | 1/31/2007 |
| Q: i have one question, i admit it is simple, but i can take either way on it. does initial velocity of ... A: The acceleration of an object is directly proportional to the force acting on the object. So if the ... | |
| uniformly accelerated motion - traffic light problem | 1/31/2007 |
| Q: Usually I can figure these questions out, but not this one....I am so stumped! A person driving ... A: I am not quite sure about your local laws regarding traffic lights: Does one have to have cleared ... | |
| air as an insulator of sound | 1/29/2007 |
| Q: I'm doing research for my science fair project. I am in the ninth grade. I do not need a solution ... A: Sound waves travel with much less damping through most solid materials than through air. Air ... | |
| Pulling a trailer | 1/24/2007 |
| Q: What is the actual physics of pulling a boat or utility trailer? Is it considered being pulled or ... A: The answer to this question depends on how you view the hinge of the trailer. If you consider that ... | |
| General Physics Question | 1/23/2007 |
| Q: Now, can you plug in the numbers and send it back to me just to make sure that I did do it ... A: I do not deliver complete answers to homework questions out of principle (and for your own long term ... | |
| General Physics Question | 1/22/2007 |
| Q: I am a non traditional college freshman. I am taking a General Physics class. I am about to pull ... A: The only formula you need in order to solve this problem is the definition of velocity v, which is ... | |
| mass density | 1/20/2007 |
| Q: One end of a wire is attached to a ceiling, and a solid brass ball is tied to the lower end. The ... A: C., The tension of the wire is equal to the weight w of the brass ball (150 N). The mass m of the ... | |
| relativity | 1/19/2007 |
| Q: Lenght contraction and time dilation in Special Relativity is puzzling me greatly. This is what I ... A: Let the rocket be 4 light-seconds long, moving with velocity v = 0.6*c in x-direction (c is the ... | |
| relativity | 1/18/2007 |
| Q: I’ve been reading some popular works on special relativity, and would greatly appreciate ... A: 1) Yes. 2) No. Only for non-relativistic velocities (i.e. < 0.1*c, where c is the speed of light). ... | |
| Anti_matter | 1/15/2007 |
| Q: What is anti matter and how do you make it? A: Your question is probably best answered on this page: http://en.wikipedia.org/wiki/Antimatter If ... | |
| how atmospheric pressure can be helpful ? | 1/14/2007 |
| Q: I am in 8th grade ! I am on project from my grade but I had little confuse to explain how ... A: I don't quite understand what kind of an answer you are expecting. What do you mean by helpful? ... | |
| how does a pulley decreases the force? | 1/14/2007 |
| Q: how does a pulley decreases the force? A: The work required to move an object a certain distance is constant. This principle is called energy ... | |
| Physics | 1/10/2007 |
| Q: We (friends) came across this question and seem to have different answers.If a can of compressed air ... A: This problem is very similar to the problem of the so called "Feynman sprinkler" (see here: ... | |
| physics:the quantum thoery | 1/9/2007 |
| Q: Sir, The planck's quantum theory proposes the energy of an electromagnetic wave to be ... A: At the end of the 19th century there was a problem in describing the spectral energy density of ... | |
| Ice | 1/8/2007 |
| Q: I am doing a science project and my problem is "What will melt faster: regular ice, koolaid ice, or ... A: The melting point of a pure substance is always higher than the melting point of that substance when ... | |
| seeking a mathamatical concept | 1/8/2007 |
| Q: i love the fact that the world is mathamatical. i would like a tatto or tattos of mathamatical ... A: If you are looking for an equation, then take a look at this article and the selection of beautiful ... | |
| What is Econophysics? | 1/5/2007 |
| Q: What do u mean by ECONOPHYSICS ? A: Econophysics is an interdisciplinary research field, applying theories and methods originally ... | |
| Length contraction and particles | 1/5/2007 |
| Q: Suppose we have a proton and electron, separated with a distance, d with respect to a stationary ... A: The electric and magnetic fields of the electron and proton are deformed by relativistic effects ... | |
| acceleration | 1/5/2007 |
| Q: I'm in seventh grade,and learning about acceleration. The formula we learned is: final velocity- ... A: Your formula is correct: acceleration a is derived from initial velocity vi and final velocity vf ... | |
| Physics in roller coasters | 1/4/2007 |
| Q: I am having a hard time finding reliable sources for learning about the physics involved in roller ... A: The centripetal force is the force acting upon an object that is directed to the center of a ... | |
| potential difference | 12/21/2006 |
| Q: I have a question about potential difference. (I am working through a first year text on my own.) ... A: 1) Yes 2) I guess it is a convention. I have read books with this convention and books which speak ... | |
| help plz | 12/21/2006 |
| Q: here thewhy is the water supply tank in a town made at suffiecient ht.?my book says its coz then the ... A: The pressure in water is higher the deeper you go (you might know this from diving in a swimming ... | |
| heat/damp | 12/21/2006 |
| Q: Why does lighting a fire in a room stop that room being damp? A: The amount of water vapour air can carry depends on the temperature. Hot air can absorb more ... | |
| understanding physics | 12/19/2006 |
| Q: so then does this mean that a small sphere of plastic would fall (on earth) faster than a much ... A: The total force on an object is gravity minus friction (air resistance). This force accelerates the ... | |
| Energy Conversion | 12/17/2006 |
| Q: I am a Junior in college and I am curious on the relationship of physical properties between lasers ... A: Watt is a unit for power. Power is energy per time unit. P = E / t So the amount of energy (in ... | |
| help plz | 12/17/2006 |
| Q: can u plz help me out with this question? when a floating piece of ice melts into water it contracts ... A: Archimedes' principle of buoyancy states that a floating body displaces a volume of water equal to ... | |
| understanding physics | 12/15/2006 |
| Q: If a hammer and a feather on the moon( or in a vaccuum), when dropped, fall at the same rate and hit ... A: Objects are accelerated by gravity at the same constant rate (g= 9.81 m/s^2 on Earth, about 1/7 of ... | |
| Vakuumfluktuationen | 12/14/2006 |
| Q: Hallo Kevin Johnson, Ich habe in einer Zeitschrift einen Artikel gelesen wo es um ... A: Hallo Alexander M, In der Quantenmechanik gibt es die Heisenbergsche Unschärferelation, die besagt, ... | |
| physics | 12/14/2006 |
| Q: Good Morning Mr. Johnson I sent you a question but here is all of the information. A train blows its ... A: Your initial question (which I rejected since I don't do homework solutions) gave some different ... | |
| Geostationary orbits | 12/14/2006 |
| Q: Subject knowledge: Almost finished by A'levels. Why is it that Geostationary satellites can only ... A: Smith, A satellite uses no propulsion once it has been put in a stationary orbit. It is given a ... | |
| Work | 12/14/2006 |
| Q: i am a grade 12 physics student, and i have a question regarding work done when an object is lifted ... A: When you take an object away and then put it back to its original position, the total work done on ... | |
| Geostationary orbits | 12/13/2006 |
| Q: Subject knowledge: Almost finished by A'levels. Why is it thAT Geostationary satellites can only ... A: Smith, All satellites orbit around the center of mass of the earth. The equator is the only ... | |
| help | 12/13/2006 |
| Q: how can you amplify sound with a tuning fork A: A tuning fork has a specific frequency that it vibrates with. When sound of this frequency hits the ... | |
| physics: motion | 12/12/2006 |
| Q: If person A is standing on the platform of a train station, watching a train head in the opposite ... A: The ball is already moving at the train's speed when it is resting in the hand of the pitcher. When ... | |
| Stationary path? | 12/12/2006 |
| Q: WHAT IS A STATIONARY PATH?I READ SOMEWHERE THAT THE LINE INTEGRAL OF AN ELECTRIC FIELD, PRODUCED BY ... A: Sorry, I overlooked your second question. "Stationary" means constant over time. So a stationary ... | |
| Car power | 12/12/2006 |
| Q: I am not the best at this kind thing so if you could give me a complete instruction list. I can uses ... A: The objective of your assignment is to spark creative thought and put to use some of the principles ... | |
| Energy | 12/11/2006 |
| Q: I had a doubt while reading a physics book. In the chapter work, power, energy, i read about ... A: The terms electrical energy and electrical potential energy could desribe different things, they ... | |
| Question about temperature | 12/11/2006 |
| Q: How come the temperature can be infinitively positve but not negative? For example, the temperature ... A: Heat is, at a microscopic level, random movement of atoms. The atoms vibrate (in the solid state) or ... | |
| Environmental / thermodynamic physics | 12/10/2006 |
| Q: I have a fairly good understanding of physics, but one thing has always bothered me. Most ... A: You have the right idea: electrical appliances do conribute to the heating of a house, but their ... | |
| Field force | 12/9/2006 |
| Q: In a wire electrons are moving? or is it the field force that is moving? how does this work? A: As you apply a potential difference (= voltage) to the wire, an electric field is built up ... | |
| Standing Wave | 12/6/2006 |
| Q: Johnson, As a first year Physics student, we have come into waves. I believe I know how to prove ... A: If the wave is time-independent, i.e. the position of the nodes and the position and amplitude of ... | |
| atomic shells | 12/6/2006 |
| Q: i want to know the abbriviations of K, L, M, N shells. Why these shells are given these alphabetical ... A: This notation goes back to the naming of spectral lines in the emission and absorption spectrum of ... | |
| voltage vs current | 12/5/2006 |
| Q: i'm a secondary school physics teacher. i made a lemon battery by connection about 24 lemons in ... A: Your lemon battery creates a considerable voltage, but it has only little power. Power is voltage ... | |
| The Doppler Effect | 12/5/2006 |
| Q: Johnson, I'm having some trouble figuring out this problem, please help! You are riding your ... A: I never give complete solutions to homework problems, but I will give you a hint: The frequency f ... | |
| hydrogen | 12/4/2006 |
| Q: How do you separate hydrogen from oxygen in water? A: The hydrogen and oxygen in water (H2O) are chemically bonded to another. To split this bond you need ... | |
| polarization | 12/3/2006 |
| Q: How would you arrange two polarizing sheets so that no light would be transmitted? A: Polarizing sheets only let light through which is polarized in one direction (e.g. horizontal). ... | |
| big numbers in popular science | 12/2/2006 |
| Q: This was quoted in Bill Bryson's 'A Short History of Nearly Everything,' from 'Microcosmos' ... A: If the number of bacteria were to double every 15 minutes, then their number would indeed supersede ... | |
| regarding air as good insulators | 12/2/2006 |
| Q: I want to ask why air is a good insulator and what are some experiments I can perform to prove that? A: I assume you mean electrical insulation. If in fact you mean thermal insulation, please correct my ... | |
| Maxwell's Equations | 12/2/2006 |
| Q: if knowing the electric vector of a plane wave travelling in free space, E(x,y,z,t) is it possible ... A: For electromagnetic waves you can use a more efficient approach and thus eventually the fact that ... | |
| Basic Physics | 11/30/2006 |
| Q: Help! I see you don't provide answers to homework problems. I have a Student Teacher as a teacher ... A: It is usually best to transform any given values to meters, seconds and kilograms (and the units ... | |
| Velocity | 11/28/2006 |
| Q: So why does the disk always win if it has the same mass and radius as the ring? (mathmatically, of ... A: I thought you already knew, from your calculations: The rotational inertia of the ring is higher ... | |
| Physics, Expansion | 11/28/2006 |
| Q: If I fill a bottle to fourth-fifth of water and put it into a freezer and leaves it overnight, what ... A: The water will freeze and since solid water has a lower density than liquid water, the ice will take ... | |
| kinetic energy | 11/27/2006 |
| Q: Is it possible to store kinetic energy into a rechargeable battery? How? A: Kinetic energy can be transformed into electric potential by means of an electrical generator (see: ... | |
| Einstein | 11/22/2006 |
| Q: I am not sure if this is your expertise and maybe you can refer me to someone who is, I liked your ... A: Albert Einstein contributed various achievements in the field of theoretical physics. His most ... | |
| Wavelength reduction | 11/22/2006 |
| Q: Is there a crystal that a laser can be sent through that would reduce its wavelength? Particularly ... A: Well, you would use the laser pointer as a pump for the laser you would have to construct outside ... | |
| acceleration/velocity/displacement | 11/21/2006 |
| Q: I am working on a project for my calculus class. I chose to look at the relationship between ... A: The unit of displacement is a length (e.g. feet, inches or meters). The unit of velocity (which is ... | |
| Wavelength reduction | 11/21/2006 |
| Q: Is there a crystal that a laser can be sent through that would reduce its wavelength? Particularly ... A: There is a device called an optical parametric oscillator that can increase the wavelength (i.e. ... | |
| Thermal Energy Transfer Equation | 11/21/2006 |
| Q: Johnson, I was wondering if there is a way to isolate the final temperature variable when trying to ... A: Two objects in thermal contact that form a closed system (no energy exchange with the surroundings) ... | |
| reference frames | 11/20/2006 |
| Q: I understand that to say that an object is in uniform motion has meaning only with reference to a ... A: Among the whole class of uniformly moving reference frames there is no "privileged" reference frame, ... | |
| orbital problem | 11/19/2006 |
| Q: I having lots of problems with orbital problems and general gravity problems, and it would be ... A: A "circular orbit with a radius of 9000 miles" is not an orbit 9000 miles above the earth's surface. ... | |
| heat transfer | 11/17/2006 |
| Q: finding the final temperature when two objects are involved in heat transfer. A: Two objects in thermal contact that form a closed system (no energy exchange with the surroundings) ... | |
| displacement / weight? | 11/16/2006 |
| Q: as the cylinder is lowered into the well, will it require more weight as it sinks deeper into the ... A: Actually a submarine needs less weight to overcome buoyancy as it sinks deeper. This has to do with ... | |
| Metal mugs | 11/16/2006 |
| Q: Just a simple question to solve an argument. Would a metal coffee mug keep liquids hotter longer or ... A: Metal is a better heat conductor than porcelain, the latter being quite a good thermal insulator. So ... | |
| displacement / weight? | 11/16/2006 |
| Q: I need help to find out how much weight would be required to sink a 4 1/2" diameter by 9.5'long ... A: The physical law relevant to your problem is Archimedes' principle of buoyancy: The buoyant force is ... | |
| Physics: vectors and scalars | 11/15/2006 |
| Q: A car moves 65 km due east, then 45 km due west. What is its total displacement? A: Out of principle I do not supply complete solutions to homework questions. But I can give you a ... | |
| Forces | 11/14/2006 |
| Q: If someone were to jump from a very high building they would be pulled down by a force of mg Newtons ... A: Since force is the change of momentum per time (the time derivative of momentum, in case you know ... | |
| i badli nidid this info | 11/14/2006 |
| Q: thanx for the info..anyway, is there a specific equation how this coin sorter counter counts the ... A: I don't see how an equation could express the necessary detection mechanism. If you just need to ... | |
| About single slit diffraction | 11/12/2006 |
| Q: To explain the single slit diffraction,we should imagine the slit as two halves.But why we need to ... A: diffraction is an interference phenomenon. You need two waves to produce interference, so for single ... | |
| Forces | 11/11/2006 |
| Q: If someone were to jump from a very high building they would be pulled down by a force of mg Newtons ... A: A jumper is accelerated by the earth's gravitational acceleration g = 9.81 m/s^2. He thus gains ... | |
| physics | 11/10/2006 |
| Q: pls how are the light dependent resistor used, mostly for security light. and how they work on there ... A: Light dependent resistors (also called photoresistors) are used as light detectors, for example in ... | |
| Lighting | 11/6/2006 |
| Q: What is the difference between lighting? What creates the difference between sunlight, laser light, ... A: Between sunlight and standard light bulb light there is no qualitative difference, it is both ... | |
| Light Intensity | 11/6/2006 |
| Q: I need to theorize how the first scientists measured the intensity of light. The question ... A: To measure light intensity one compared the measured light source with a light source of known ... | |
| Relativity vs. QM | 11/4/2006 |
| Q: I have a very basicIt is often said that Einsteinian relativity and quantum mechanics are ... A: The incompatibility between relativity and quantum mechanics is not something you would encounter in ... | |
| potential energy - ground state - stable state | 11/1/2006 |
| Q: WHAT HAPPENS TO THE POTENTIAL ENERGY WHEN THE SYSTEM IS STABLE? A: Your caps key seems to be stuck. Potential energy is always defined in relation to a ground state. ... | |
| physics -11th grade | 11/1/2006 |
| Q: The current theory of the structure of the earth, called plate tectonics, tells us that the ... A: I don't provide homework solutions out of principle, but I can give you a few hints: One dimension ... | |
| Falling Bridges | 10/31/2006 |
| Q: I am a high school physics student, and I am doing a project on bad physics in movies- in ... A: How a structure collapses depends on where it is damaged. If the strong steel rope that runs across ... | |
| Magnetism | 10/30/2006 |
| Q: Sir, Is there any element or compound that does not allow a magnetic field to pass through it and ... A: The compound you ask for would have to change the magnetic field without being changed by it. In ... | |
| Tension | 10/30/2006 |
| Q: A small block of mass m1=0.500 kg is released from rest at the top of a curved wedge of mass m2=3.00 ... A: use the conservation of total momentum to get the velocity of the wedge (v2): m1 * v1 + m2 * v2 = 0 ... | |
| Physics Research | 10/29/2006 |
| Q: I'm a high school student, and part of my graduation reqiurments (as an IB student) is to do an ... A: Both topics sound good. I don't know the requirements for the essay, but it seems like you need to ... | |
| calculating useful energy output | 10/29/2006 |
| Q: In a lab excercise where a 1.1 kg sample of water with an initial temperature of 12 degrees celcius ... A: The energy gained by the water Q=mct is the useful energy. The difference between the energy ... | |
| friction | 10/28/2006 |
| Q: Could you explain why friction is reduced when one of the sliding surfaces is a soft material(e.g. ... A: There are two slightly different forms of friction: static friction (sticking) and dynamic friction ... | |
| Rotational Dynamics | 10/27/2006 |
| Q: I have a question on rotational dynamics. Let's say we have a long horizontal table and two balls ... A: If you apply the same torque for the same time on both balls, then they will get the same angular ... | |
| Science Project - Friction | 10/27/2006 |
| Q: When I say points I mean the topics of each paragraph in a research paper. Ex., there are ten ... A: If I understand it correctly the "points" of discussion are parameters to be varied in the ... | |
| Science Project - Friction | 10/26/2006 |
| Q: Johnson, I'm a 10th grader doing a science fair project. My question is "Can a slower ... A: I don't quite understand what you are trying to show and why it is necessary to discuss "three ... | |
| pipe flow - hazen williams formula | 10/24/2006 |
| Q: I must use the hazen-williams formula to determine the minumum pipe diameter from A elev=198.1m to B ... A: You can just use the empirical Hazen-Williams equation to solve the problem. Just solve it for the ... | |
| Application of Newton's Laws of Motion on a nonequilibrium system | 10/20/2006 |
| Q: This question ahs to do with a paraglider that is flying horizontally at a constant speed. Assume ... A: If the vertical lift force of 1500 N makes him fly horizontally, then this is the force that exactly ... | |
| scaling - inverse-square law | 10/19/2006 |
| Q: Something has been bothering me about the "scale" bench test that is often done. It is the ... A: A human being can bring its foot as close to a wall as a fly, so if the inverse square law were the ... | |
| free fall | 10/18/2006 |
| Q: we had this experiment in physics. can you please help me answer this: an arrow is shot vertically ... A: I only give hints, never complete solutions to homework. After the arrow has left the bow, it is in ... | |
| musical acoustic physics | 10/18/2006 |
| Q: I'm having trouble figuring out one of my college level physics problems. Your advice/tips on how to ... A: I just realized that the subject of your question implies a totally different approach on the ... | |
| Resonance and resonance destruction | 10/16/2006 |
| Q: I once saw the people at Myth Busters shatter a wine glass by finding its resonance frequency. I ... A: I will answer all your questions in one answer here. Your questions were: I once saw the people at ... | |
| uranium enrichment | 10/15/2006 |
| Q: My knowledge level is that I've graduated college, but I didn't take a physics course. That being ... A: There are different isotopes of uranium, that is uranium atoms with different numbers of neutrons in ... | |
| Light intensity | 10/14/2006 |
| Q: I am a student at john bowne high school and i don't know anything about light intensity, in fact i ... A: There are several slightly different units of "light intensity" that could be meant. But the one ... | |
| translational equilibrium | 10/14/2006 |
| Q: First year college physics. I know that an object is a rest or in constant velosity with no ... A: In a translational equilibrium all the forces on an object cancel each other out, in the sense that ... | |
| physics | 10/13/2006 |
| Q: no knowledge of physics. Suppose you are going over Niagra falls in a barrel and during the fall ... A: Your intuition is right, the apple would remain stationary to the person. The reason for this is ... | |
| measuring different kinds of energy | 10/13/2006 |
| Q: How can 100 joules thermal energy be equated to 100 joules mechanical energy, when they are used to ... A: > What are egg drop questions? Very many American high schools conduct an so called "egg-drop ... | |
| Three-dimensional coordinates | 10/12/2006 |
| Q: It seems that it's getting me somewhere but I still have some things unclear. Mostly about angles. I ... A: If I understood you correctly the camera should orbit the object at a constant distance while the ... | |
| Three-dimensional coordinates | 10/12/2006 |
| Q: I am making a 3D game and I came to a very unpleasent situation. I cannot make the camera orbit ... A: If I get it correctly then cameraX, cameraY and cameraZ are the position coordinates of the camera, ... | |
| Seatbelts and Helmets / Physics | 10/11/2006 |
| Q: Saftey experts say that about half the people who die in car crashes would survive if they wore ... A: Let us separate the two issues of seat belts on the one hand and helmets on the other hand. A seat ... | |
| sign of the charge | 10/10/2006 |
| Q: two uncharged metal ball, x and y, stand on glass rods. a third ball z carrying a positive charge, ... A: I don't solve homework problems, but I can give you a starting hint. Charges of the same sign repel ... | |
| physics (projectile motion) | 10/10/2006 |
| Q: Kevin, I am not looking for a solution, but rather assistance with the formula. I am a junior in ... A: Since you are only interested in the height of the jump you can disregard the horizontal component ... | |
| stumped on fish | 10/9/2006 |
| Q: I'm working on some problems, working off the internet, 4 different books, help from friends. There ... A: assuming the given data is correct, you solve the problem in the following way: Since the salmon is ... | |
| Passing C | 9/29/2006 |
| Q: I know a little about physics. I understand, or at least except, that you cannot surpass the speed ... A: This concept is the basis of the fictional "hyperspace travel" and the "warp drive" in Star Trek. ... | |
| experimental work | 9/28/2006 |
| Q: i did an experiment which produced a graph with a curve that looked like an exponential graph. what ... A: You have a plot of f(x) against x and it looks exponential. In order to determine whether f(x) is ... | |
| Friction Coefficients disconintuity | 9/27/2006 |
| Q: Could you please explain why there is a discontiniuty between the static coefficient and the kinetic ... A: The mechanism of friction is not yet fully understood on a molecular basis. There exist very good ... | |
| the atom | 9/25/2006 |
| Q: What does "splitting an atom" mean? Is an atom really split or is that just an expression? How ... A: In the process of nuclear fission the nucleus of an atom is really split into several parts. Since ... | |
| Speed of light | 9/24/2006 |
| Q: How can we be sure that we can't travel at the speed of light? We as humans are made of matter, but ... A: There are several ways to estimate the total energy of the universe. One can sum up the mass of all ... | |
| Path of least resistance | 9/24/2006 |
| Q: So basically all materials conduct electricity but the degree of strength varys. So there is a bit ... A: Right, some of the current is passing through the professors hands. There are good conductors, bad ... | |
| Speed of light | 9/23/2006 |
| Q: How can we be sure that we can't travel at the speed of light? We as humans are made of matter, but ... A: When you accelerate a mass, you add to its kinetic energy. This added movement energy is equivalent ... | |
| Path of least resistance | 9/22/2006 |
| Q: today my profeessor shorted out a 12V car battery with a piece of bare metal in his bare hands. Why ... A: If I understand you correctly, your professor shorted the battery with the piece of metal, which he ... | |
| football | 9/22/2006 |
| Q: This is a physics question about football. Since I am not familiar with American football, I have ... A: Just ignore the football stuff and solve this problem: Person A (the running back) and person B (the ... | |
| Branes and The Big Bang | 9/21/2006 |
| Q: My question is this, simply, is science any closer to understanding: 1- What's smaller than a ... A: 1. In theoretical physics, branes or p-branes are spatially extended objects that appear in string ... | |
| osmosis and diffusion. | 9/20/2006 |
| Q: I'm really confused with these questions and I would appreciate your answering. Submerge bag in ... A: 1. The plain water bag is your control. It should not exhibit osmosis. If it does, you need to check ... | |
| physics | 9/19/2006 |
| Q: the pressure of a given depth below the surface of a static fluid is the same everywhere, but in a ... A: 1. I am not sure what you mean by "pressure decrease along the direction of motion." Perhaps you ... | |
| Errors | 9/18/2006 |
| Q: In an experiment to find the sensitivity of a metallic conductor, the following readings were ... A: I don't solve homework problems. If you have a specific question regarding a certain step in ... | |
| PHYSICS | 9/17/2006 |
| Q: what does n implies in [Asin (n*3.14*x)/l]? what is potential and what is the role of potential in ... A: You give nearly no context to your question, which is a bit vague to me, but I guess you are ... | |
| physics | 9/16/2006 |
| Q: This is not homework. I realize that color is related to the electro magnetic frequency. If someone ... A: The light of a regular lightbulb, like the one in a flashlight, is white light, which is a mixture ... | |
| physics | 9/16/2006 |
| Q: what factors other than the volume a gas occupies affect its pressure? why can some people float in ... A: 1. The ideal gas law (as a first approximation of the state of a gas) relates the relevant ... | |
| physics | 9/15/2006 |
| Q: im stick on this problem.. can u give help me on this problem? Many computers keyboards operate on ... A: this sounds very much like a homework question, which I don't completely answer, since they are your ... | |
| astronomy | 9/13/2006 |
| Q: Why does the moon gain orbital energy and recede from the earth while two co-rotating neutron stars ... A: The system earth-moon does not give off or take up energy, so between the moon and the earth energy ... | |
| Particle Accelerator | 9/8/2006 |
| Q: Is it possible to make a very simple particle accelerator for a science fair project? Or at least a ... A: did you know that you most probably have a particle accelerator at home? The cathode ray tube of a ... | |
| Polarized Light | 9/7/2006 |
| Q: do you know much about this? Please advise Thanks Dean Cox A: Your question is very general, so I would like to answer by referring you to a site to read: ... | |
| satellite motion | 9/6/2006 |
| Q: kevin, why satellites dont fall down over earth service?..which making it spin around?..i know u may ... A: A satellite in a geostationary orbit (35,786 km above the equator) is moving at a speed of 11,068 ... | |
| Speed | 9/6/2006 |
| Q: What would happen if a car pulling a trailer was going 55mph another car was going just fast enough ... A: Let's say that the car boarding the trailer moves 5 mph faster than the trailer. It retains its ... | |
| universal states | 9/3/2006 |
| Q: Kevin, my knowledge level = retired PhD chemist. The energy of an electron in free space = the ... A: The energy of an electron can be either continuous (the free state) or quantized (in the presence of ... | |
| Theory of relativity | 9/1/2006 |
| Q: What exactly is the theory of relativity? Does it suggest that matter itself is energy hence why ... A: the theory of relativity is a framework theory, which tells us how space and time are related to one ... | |
| particle physics | 8/29/2006 |
| Q: Knowledge level : college physics - undergrad junior level Is it possible that spacetime has a ... A: I don't quite understand what you are trying to say, sorry. But your question > Is it possible ... | |
| Just some simple questions | 8/28/2006 |
| Q: I have some questions that I thought you might be able to answer. Can a penny dropped from a very ... A: Can a penny dropped from a very tall building kill a person at ground level? Yes. It gains enough ... | |
| Synchrotron | 8/27/2006 |
| Q: I am a high school student studying the synchrotron and its applications and I did a question ... A: Yes, your estimate is realistic. The particles in modern accelerators reach velocities very close to ... | |
| polemoscopes | 8/26/2006 |
| Q: What are polemoscopes? What are its uses? Your reply would really help me a lot.... I will be ... A: There are two uses and thus two slightly different constructions of a polemoscope. The first use ... | |
| physics | 8/26/2006 |
| Q: I have been watching a guy on tv do amazing things. He can pass through glass windows of restaurants ... A: The tricks used by "magicians" (or illusionists as these skilled entertainers should more aptly be ... | |
| a-bomb | 8/25/2006 |
| Q: I was wondering what happens to the uranium in an atomic bomb after the fission thing happens? Do ... A: Sorry, I clicked the wrong button, so you got a negative reply first. Of course you don't need to ... | |
| Inertial navigation systems | 8/25/2006 |
| Q: As far as my knowledge level I majored in chemical engineering in college, and have a very good ... A: A gyroscope is a device for measuring or maintaining orientation, based on the principle of ... | |
| black umbrella protects us from heat but black dress make us feel heat | 8/24/2006 |
| Q: black umbrella protects us from heat but black dress make us feel heat how is this happening A: Black surfaces have the highest absorption rate for electromagnetic radiation (light and heat). This ... | |
| physics | 8/23/2006 |
| Q: why do ships floats? A: A ship floats because of its buoyancy. Buoyancy is an upward force on an object immersed in a ... | |
| elevator motion | 8/23/2006 |
| Q: a man in an elevator drops a coin. It takes 5 seconds to hit the floor. Will the time increase if ... A: The time it takes for the coin to reach the "floor" (5 seconds) would indicate a free fall for ... | |
| dimentions | 8/22/2006 |
| Q: I taking a plane to Florida. The airliner says I can take one carryon bag with the dimentions ... A: It does not matter, which dimension is height, length or width. Let's say you have a suitcase that ... | |
| Cold laser? | 8/18/2006 |
| Q: Being concentrated light I would expect a powerful laser to be very hot. But are there lasers out ... A: the heat transfer of a laser to a surface depends on the laser's wavelength and the absorption ... | |
| I am new at physics i need help | 8/18/2006 |
| Q: a car with an inital speed of 23.7/km/h accelerates at a uniform rate of 0.92 m/s2 for 3.6 s find ... A: use the equations for uniformly accelerated motion: v(t) = v0 + a*t v(t) is the velocity at time ... | |
| Relativity | 8/17/2006 |
| Q: Scientists say that it would take 15 years to get to the nearest star system going the speed of ... A: While in the star's inertial frame 15 years would pass until you reach it, in your own inertial ... | |
| Magnetic Motion? | 8/15/2006 |
| Q: I realize that the idea of harnessing more energy from something than is put in (ie: perpetual ... A: In order to pull a magnet away from another magnet you consume (at least) the same amount of energy ... | |
| MCAT Help! | 8/10/2006 |
| Q: I really appreciate it. Just to be sure, "the number of light particles that pass by per second is ... A: > Do you have any advice on how I can visualize light while > taking into account both definitions ... | |
| MCAT Help! | 8/9/2006 |
| Q: I am a bioengineering major (thus limited to calculus-based, college level physics) studying for the ... A: Light is electromagnetic radiation and since it is a quantum field phenomenon, there is a duality ... | |
| gravity | 8/8/2006 |
| Q: i was wondering what the gravitational forces would be on an object that was dropped down a hole ... A: You already asked me this question the day before and according to my stats you also already read ... | |
| gravity | 8/7/2006 |
| Q: i've been asking a lot of people this, teachers etc. and none of them appear to be able to give me a ... A: Let's consider two cases: If the hole is totally empty (vacuum) then you would accelerate ... | |
| radiation | 8/3/2006 |
| Q: Is it the case that a blackbody at any temperature above absolute zero will emit at least some ... A: In Planck's formula for the black-body radiation (cf: ... | |
| Gravity | 8/2/2006 |
| Q: Sorry to bother you. My four year old has just asked why there is no gravity in space, and I cannot ... A: There is in fact gravity in space. But the force of gravity decreases sharply with distance from the ... | |
| The Smallest Particle | 7/28/2006 |
| Q: I am just trying to keep up with the latest physics. I was waching a cosmologist on TV and he ... A: Atoms are made of a nucleus and a shell of electrons. The nucleus is made of protons and neutrons. ... | |
| falling objects | 7/26/2006 |
| Q: thoughtful, and prompt reply. I think I get it now, but does that mean that the bullet fired at ... A: since you are assuming no air resistance, the bullet will hit the ground with a horizontal speed ... | |
| falling objects | 7/25/2006 |
| Q: I'm 47! and know VERY little about physics. I came across this question in a book on critical ... A: both the fired bullet and the dropped bullet have an initial vertical velocity of zero. The only ... | |
| Motor Spent? | 6/29/2006 |
| Q: Why does an electric motor need so much electricity to rotate productively? Which part of the motor ... A: a very detailed description of the many variants of electric motors can be found at ... | |
| electrical whine or hum | 6/28/2006 |
| Q: I love wikipedia but need a definite answer as I am using this as a descriptive comment in my novel ... A: I must frankly admit that I do not know the origin of the humming or whining sound you described. In ... | |
| string theory | 6/27/2006 |
| Q: What are the "strings" in string theory made of? When I think of a string, I envisage cat gut, steel ... A: the strings of string theory are the elementary constituents of matter. They cannot be made of ... | |
| general physics | 6/25/2006 |
| Q: 3 resistors are connected in parallel to a battery. R1 has an electrical potential of 4.0 volts, R2 ... A: since the potential of electrical elements in parallel is the same, R3 has the same potential as R1. ... | |
| earth's gravity | 6/12/2006 |
| Q: does the gravity or the force ,that pull every object toward the center of the Earth pulls all ... A: Gravity is a force by which two masses attract each other. The Earth and the Moon attract each other ... | |
| fission | 6/10/2006 |
| Q: I am a high school student.Well i am really confused about Fission reaction.The problem is that I ... A: The mass of the fission products is approximately 0.1% lower than mass of the fuel. You have to use ... | |
| singing | 6/8/2006 |
| Q: I am trying to become a good singer and I just have tons of questions about the science behind ... A: I am not an expert on physiology (the study of the mechanical, physical, and biochemical functions ... | |
| Electricity | 6/4/2006 |
| Q: Sir, Please help I am very interested in electricity and I am determined on studying it. ... A: I am afraid I cannot explain fundamentals here through this medium, but I can give you a link where ... | |
| paradox for electricity | 6/1/2006 |
| Q: The increasing brightness of the bulb is an indication that the temperature of the bulb filament ... A: I have just noticed that you asked this question of several other experts, too. In my humble ... | |
| forces | 5/31/2006 |
| Q: Why can't you follow the opposite reaoning of f=ma that acceleration is constant(I mean it's not ... A: without other external forces, the force that the carts exert on each other leads to an ... | |
| Resonation | 5/30/2006 |
| Q: Why can you shatter a drinking glass with a certain frequncy, but not a square peice of glass like a ... A: As you probably know, acoustic resonance is the tendency of an acoustic system to absorb more energy ... | |
| forces | 5/29/2006 |
| Q: Two carts are pushed apart by an expanding spring, as shown in the diagram below[see diagram at the ... A: your reasoning (Newton's third law) is exactly to the point. If you plug this same force (1N) into ... | |
| power | 5/28/2006 |
| Q: A truck weighing 3.0 × 10^4 newtons was driven up a hill that is 1.6 × 10^3 meters long to a level ... A: Work is distance times the force along that distance (parallel to the path). Since for the ... | |
| electric field | 5/28/2006 |
| Q: An object with a net charge of 4.80 × 10^–6 coulomb experiences an electrostatic force having a ... A: since the charge is given as 4.80 × 10^–6 coulomb and not - 4.80 × 10^–6 coulomb ... | |
| speed of light constant? | 5/22/2006 |
| Q: Kevin, I heard of a theory through the open university programmes in the UK a couple of years ago ... A: the vacuum speed of light is a constant. This is the foundation of Einstein's special relativity ... | |
| motion | 5/19/2006 |
| Q: Can the speed of a particle be negative? can the velocity of a particle be negative?support your ... A: Since speed is defined as distance divided by time, you would either need the distance or the time ... | |
| Light | 5/16/2006 |
| Q: Can you describe How Light can be Reflected, Refracted and Diffracted? Thanks. A: This is a very broad question and since you don't specify your knowledge level (i.e. high school ... | |
| Theoretical question on relativity | 5/12/2006 |
| Q: Consider a train , its proper length = 375000 km , traveling at a speed of 180000 km/sec (0.6 of ... A: The speed of light is constant for all observers in inertial systems. This is the one fundamental ... | |
| Einstein | 5/11/2006 |
| Q: First of all, physics is not my forte. My background is accounting and now I'm pursuing a degree in ... A: In his so called "miracle year" or "wonder year" (1905) Einstein published three groundbreaking ... | |
| Heat and Temperature | 5/9/2006 |
| Q: how are heat and energy different? A: Heat is a form of energy (the other forms being kinetic energy and potential energy). See these ... | |
| work &torque | 5/8/2006 |
| Q: so the answer is 17.4 n*m why does my solution manual say W=torque * theta 10 Nm * (100 ... A: I cannot figure out what "rev" is supposed to mean here. But if I use your formula > 10 Nm * (100 ... | |
| work &torque | 5/6/2006 |
| Q: Blair is playing the slot machines. She puts in her quarter and pulls down the arm with a torque of ... A: Although this sounds like a bona fide homework problem, I nevertheless choose to answer, since I can ... | |
| nuclear forces | 5/1/2006 |
| Q: how do you explain weak nuclear force to high school physics sudents (regular and Pre-AP) A: sorry, I committed an error in my previous response. A neutron of course decays into a proton and a ... | |
| light ray | 4/29/2006 |
| Q: I hope I'm finding you in the best of health. A ray of light goes from air into Lucite then back ... A: The ASCII graphics you entered are not rendered well through the text processing of AllExperts, but ... | |
| e-m/relativity | 4/28/2006 |
| Q: Supposedly in classical e-m an accelerating charge radiates. If so, why? If so, then does an ... A: the Maxwell equations governing electrodynamics already imply special relativity. There exist no ... | |
| general physic | 4/27/2006 |
| Q: Sir, Why the morning sun looks red ? A: Sunlight (white light) is composed of all colors of the visible spectrum, i.e. light of all visible ... | |
| Wind resistance and running | 4/25/2006 |
| Q: I recently was added to the list of physics experts and have tackled a question that I find that I ... A: It's nice to hear from a "colleage" from time to time. The "calories" used in fitness manuals and ... | |
| sonic booms | 4/24/2006 |
| Q: I'm in 7th grade and am studying at home in Montana and wonder why a bullet doesn't make a sonic ... A: A sonic boom is only generated by an object moving at supersonic speed. See this page for an ... | |
| the mass (weight) of the Earth? | 4/23/2006 |
| Q: How do scientists measure the mass (weight) of the Earth? A: the mass of the Earth cannot be measured directly, but one can do it indirectly. Henry Cavendish did ... | |
| photon spin | 4/22/2006 |
| Q: i have read that "if any object traveled in the speed of light time will stop relative to it" , ... A: In the co-moving system of the photon traveling at the speed of light time stands still. Now the ... | |
| Advance Vector (Law) | 4/20/2006 |
| Q: Where can I learn more about those various law of vector from basic to advance, free, on the ... A: I am not sure if I understood your question correctly. If you are inquiring about vectors then I ... | |
| Speed of Light and Time Dilation | 4/18/2006 |
| Q: I have read that as an object's speed increases, time "slows down" and that if an object were to be ... A: From my teaching experience I know that single aspects of relativity theory cannot be truly ... | |
| resistance and circuits | 4/17/2006 |
| Q: I hope I'm finding you in the best of health,as always. I'm extremely confused on one aspect of ... A: I will try my best :-) A solid electrical conductor is a lattice of atoms that are bound to each ... | |
| Gravity, Centrifugal Force and Earth Rotation | 4/14/2006 |
| Q: This is going to sound bizarre, but with the earth's rotational speed as fast as it is, why do we ... A: the Earth's rotational speed is not nearly fast enough for the centrifugal force to overcome ... | |
| load | 4/12/2006 |
| Q: Johnson, I am Dian, from Indonesia, I am in 11th grade at SMU Kebumen Highschool, Indonesia. My ... A: the force on an area A of the pool floor is equal to the weight of the water column above it. Water ... | |
| Light wavelengths | 3/26/2006 |
| Q: I have a question about light. I am not very knowledgable about science or anything of a worldly ... A: The electromagnetic spectrum is in theory infinitely wide, with wavelengths between zero and ... | |
| Reflected light intensity | 3/25/2006 |
| Q: I have a question that I've been wondering about for some time. When you respond,keep in mind I've ... A: there is no mirror that can reflect 100% of the light that hits it. The best mirrors would reflect ... | |
| electromagnetism | 3/24/2006 |
| Q: how can heat be reflected, refracted or diffracted A: heat is just electromagnetic radiation, like light, just with a larger wavelength. The same ... | |
| Gravity | 3/21/2006 |
| Q: I am an amateur researcher now days I am researching on a project concerning gravity. Can you ... A: The Earth has a magnetic field: http://en.wikipedia.org/wiki/Magnetic_field_of_earth Read here ... | |
| Quantum+Charges | 3/19/2006 |
| Q: 2 questions,hope u don't mind.Level:16yr od studying in class 12th. 1.Is there any kind of a ... A: 1. There is no known reaction in which the law of charge conservation is violated. The theory ... | |
| Dear Johnson, How can light... | 2/13/2006 |
| Q: How can light passes through glass while it can't pass through something else thinner than the glass ... A: Light passes through glass because light in the visible spectrum is not absorbed by the atoms or ... | |
| heat transfer | 2/9/2006 |
| Q: I want to review my knowledge about physics. i want to have answer my question. so please.. 1. does ... A: 1. Heat can be conducted by gasses and liquids as well, but for them convection is the more ... | |
| Cathode ray oscilloscope | 2/6/2006 |
| Q: Sir, 1.If length of CRO tube and the frequency of the input signal is adjusted,velocity of electron ... A: The principle of relativity is not violated by an electron beam. I am not sure what kind of ... | |
| physics | 2/6/2006 |
| Q: What are the forces acting on an object at free fall? A: A free fall is the uniformly accelerated motion of a mass in a homogenous gravitational field. So ... | |
| Black Holes | 2/3/2006 |
| Q: I heard someone say that black holes emit x-rays. Is this really true? If so, how can anything be ... A: Smith, The x-rays do not really leave the black hole, they are produced at the event horizon of the ... | |
| physics | 2/2/2006 |
| Q: I am 9 years old and in the 4th grade. I would like to know about air compression (I think). When I ... A: When you blow air into the sealed bottle, you raise the gas pressure in the bottle. During this ... | |
| physics | 2/2/2006 |
| Q: Kevin, A while ago I asked a question about light with very short wavelenths. The question was: ... A: The naturally observed doppler shifts in the electromagnetic spectrum (blue and red shifts) are all ... | |
| physics | 1/31/2006 |
| Q: If Seawater is desalted by freezing,then where does the salt go? A: salt has a higher solubility in water than in ice and thus as ice forms, the salt at the surface of ... | |
| Mechanics | 1/30/2006 |
| Q: Sir, 1) Consider two solid spherical balls one made of wood and other made of iron having the same ... A: M, The moment of inertia of a sphere of homogenous mass M with radius R around its center is J = ... | |
| Plastic materials and magnetic fields | 1/25/2006 |
| Q: Assume you built a coil and you use a plastic material to wind the copper wire around it and form ... A: plastic does not influence a magnetic field at all. Although if you want to build a strong ... | |
| physics | 1/24/2006 |
| Q: (Knowledge level:basic) What would be the properties of light with a very sort wavelength, close to ... A: The shortest known wavelengths of light (= electromagnetic radiation) is about 1 picometer or 10^-12 ... | |
| Light speed | 1/21/2006 |
| Q: It is accepted (relativity theory) that the light speed is a limit that a particle-body can not ... A: Relativity is a whole complex of interrelated phenomena and a good understanding requires some ... | |
| Component Velocities | 1/17/2006 |
| Q: I am a first-year high-school physics teacher (with a B.S. in Chemistry), and I'm looking for a ... A: this is the simplest way to solve the problem. Make sure your students understand that this motion ... | |
| what should i write in... | 1/16/2006 |
| Q: what should i write in my results , im confused in the diffrences between ... A: Data The raw results of an experiment are the data: - settings of the experiment - readings of ... | |
| Parallel universes on a quantum scale... | 1/12/2006 |
| Q: I have a question regarding the possibilities of parallel universes or the whole scale of different ... A: Hell Silvain Hooglander, ... and inside what we call quarks are again whole universes of a much, ... | |
| Waves | 1/12/2006 |
| Q: Happy new year! I am studying Physics B at A Level. Could you please explain the difference ... A: A transverse wave is a wave where the oscillation (the amplitude) is perpendicular to the direction ... | |
| efficiency | 1/11/2006 |
| Q: What happens to the efficiency, as the inclined plane is made steeper? Explain why this happens. ... A: The efficiency of an energy conversion is the ratio between the (kinetic and potential) energy ... | |
| Walking on the ocean floor in overturned canoes | 1/10/2006 |
| Q: I am not sure if this question actually relates to physics, but I am hoping you will be able to ... A: This is a bona fide physics question. The two factors determining whether an object floats or sinks ... | |
| Color | 1/8/2006 |
| Q: What is the first color seen in the morning and the last color seen at night? A: There are two ways of understanding your question. The first would be: What is the last color of ... | |
| physics | 1/5/2006 |
| Q: I am in 4th grade and doing research for my science fair project. my question is what will roll down ... A: My guess is that the full can will be faster, since it has a lower ratio of moment of inertia to ... | |
| Special Relativity | 1/5/2006 |
| Q: any help would be useful or a general point in the right direction would be great. An electron of ... A: The positron is the anti-particle of the electron, so on collision they annihilate each other, ... | |
| Special Relativity | 1/5/2006 |
| Q: any help would be useful or a general point in the right direction would be great. An electron of ... A: A particle with a mass m has the energy equivalent of E=mc^2. Fortunately the mass of the B*-mesons ... | |
| Energy | 1/4/2006 |
| Q: I am having a hard time understanding how to answer this problem for an honors high school physics ... A: there is even more information missing in this problem than just the mass. The original velocity, ... | |
| Plane on conveyor | 12/18/2005 |
| Q: I just wanted to ask you about the plane on a conveyor question I have seen on here a couple of ... A: Now I am really interested in why this question comes to me from many different people. Please tell ... | |
| projectiles thrown horizontally | 12/17/2005 |
| Q: I hope I'm finding you in the best of health. I'm in High school. By projectiles, when throwing ... A: You must distinguish between two phases of a throw: 1) From rest, the object is accelerated (e.g. ... | |
| light | 12/17/2005 |
| Q: When an aircraft flies faster than the speed of sound,a lound bang is produces called the sonic ... A: A massive object cannot reach the speed of light, the absolute "speed limit" of the universe, the ... | |
| rainbow | 12/16/2005 |
| Q: would you please tel me why rainbows are seen as curved.There must be a very simple explanation for ... A: Raindrops diffract light at a certain angle (about 42°, slightly different angles for different ... | |
| Gravity is constant at everywhere at Earth? | 12/16/2005 |
| Q: .. Im actually searching for the answer of this question that "Is gravity constant everywhere at ... A: Gravity is a force that is dependent on the distance of the centers of mass of the two bodies that ... | |
| acceleration | 12/16/2005 |
| Q: if it were not for air resistance, why would it be dangerous to go outdoors on rainy days A: this sound a bit like a homework question, and out of principle I don't do someone elses homework ... | |
| Photoelectric effect | 12/14/2005 |
| Q: If you strike a match above a negativly charged golf-leaf electroscope (and certain other conditions ... A: You are right, the electrons must have left the electroscope. Even though you might not have touched ... | |
| giving theory | 12/13/2005 |
| Q: JOHNSON . HOW CAN I GIVE A THEORY IN PHYSICS AND BE IN TUCH WITH PHYSICS SCIENTISTS? I HAVE A THEORY ... A: You could post your ideas in a physics discussion board like one of theose listed here: ... | |
| Airplane on moving runway | 12/13/2005 |
| Q: --- A plane is standing on runway that can move (some sort of band conveyer). The plane moves in one ... A: I had exactly the same question last week from someone else. Please tell me where you got the idea ... | |
| Energy and Molecules | 12/10/2005 |
| Q: My Knowledge level is not that great, High School Graduate Level. I have what should be a fairly ... A: I assume you arrived at your conclusion > Energy is equal to matter at twice the speed of light by ... | |
| perpetual energy | 12/9/2005 |
| Q: I have no qualifications in physics but have been obsessivly interested all my life and to that end ... A: as the lever's handle is attracted by the orbiting satellite, the satellite is also attracted by the ... | |
| Upper Echelon Physics | 12/9/2005 |
| Q: Greetings, First, my background as your instructions indicate: I am a physics undergraduate at a ... A: to test something that has not been part of the course - either in the lecture, a tutorial or the ... | |
| physics | 12/8/2005 |
| Q: what technology the reflection glass has? A: You asked: > what technology the reflection glass has? I do not understand your question. What do ... | |
| density | 12/8/2005 |
| Q: Okay, here goes. When a car is compacted at a wrecking yard, for example, does it get heavier as it ... A: The car's mass stays the same, whether it is compressed or not. The title of your question ... | |
| Diffusion/Osmosis Experiment | 12/7/2005 |
| Q: I'm in an Intro to Physics course in my freshman year of college. I have no physics background, and ... A: The controls in your experiment are glucose concentration AND temperature. For each combination of ... | |
| Quantum Mechanics | 12/6/2005 |
| Q: Why can't a solid be cooled down to the point where it has zero energy? A: The third law of thermodynamics states that the entropy S of a perfect crystal at absolute zero or ... | |
| the apparent density of matter | 12/5/2005 |
| Q: My level: layman. Why do objects feel dense and hard to us, though they're mostly empty, "fluffy"? ... A: your intuition is right about this: we are similarly constructed (also made up of matter) The ... | |
| ROTATIONAL KINETIC ENERGY | 12/5/2005 |
| Q: 14E=14M+14CSquared. 2 WEEKS ROTATIONAL KINETIC ENERGY=2M*2CSquared = 2 LIGHT WEEKS ... A: I don't know if you mean something right, but the way you state it in your question it is wrong. ... | |
| Acceleration | 12/4/2005 |
| Q: My son asked me this and I have no answer! Please help! Why does a moving train passing another ... A: there are two effects contributing your and your son's observation. 1) If you watch a moving ... | |
| Physics Research | 12/4/2005 |
| Q: I am doing an experiment for my 8th grade science class about how adding a percentage of an electric ... A: you should research under the category of (elementary/Newtonian) dynamics. The concepts to use are ... | |
| will the plane take off? | 12/2/2005 |
| Q: Plane=jumbo jet A plane is standing on a runway that can move (some sort of band conveyer). The ... A: let's first consider a car on that sort of a conveyor belt: The car transmits a force onto the ... | |
| love physics | 12/1/2005 |
| Q: what is the relation between life and physics A: physics is the science of matter and its interactions. Since biological life is bound to matter, ... | |
| Fiber Optic Question | 11/30/2005 |
| Q: I'm a total beginner to fiber optics. I'm using a strand of plastic fiber optic to channel light ... A: the aperture is the angle under which an optical device can gather or emit light. If you shine light ... | |
| particles/light | 11/30/2005 |
| Q: Down to the electron level, how do objects have their own colour, and how is it that water, metals ... A: the electronic structure of a molecule or a crystal or metal lattice determines which wavelengths of ... | |
| particle | 11/29/2005 |
| Q: .I am over 40 years old and have just recently developed a keen interest in mechanics. i have ... A: modelling the motorcycle as a particle (a pointlike mass) neglects the geometry of the bike and thus ... | |
| whoa! chaotic systems in synchronization | 11/27/2005 |
| Q: It's very generous of you to volunteer your time like this - philanthropic, even. I appreciate it. ... A: sorry for letting it sound mundane, but most discoveries in Science are reached step by small step, ... | |
| coefficient of friction formulas | 11/27/2005 |
| Q: I hope I'm finding you in the best of health. A 60kg boy is on a 15kg sled. He is pushed along a ... A: your question was: A 60kg boy is on a 15kg sled. He is pushed along a level path of snow where ... | |
| Inducitance | 11/26/2005 |
| Q: My name is Julian. i was wondering if you could please help me out with a physics problem. I would ... A: Your question was: Suppose the inductance is 0 (L= 0 H) in a series circuit. The rms voltage across ... | |
| pH factor and salt solubility | 11/26/2005 |
| Q: Why does higher pH of water decrease the solubility of salt? A: salt dissolves best at a pH value of 7 (=neutral). Salt (e.g. table salt NaCl) dissolves in the ... | |
| whoa! chaotic systems in synchronization | 11/24/2005 |
| Q: It's very generous of you to volunteer your time like this - philanthropic, even. I appreciate it. ... A: fireflies and pendulums are not chaotic as single systems. Only their slighly different frequencies ... | |
| Dead Sea | 11/24/2005 |
| Q: What is the density of sea water in the Dead Sea? A: The density of pure water is defined as exactly 1 kg/l, since 1 kg is defined as the mass of 1 l of ... | |
| pulling a large object | 11/21/2005 |
| Q: If one was to pull a large object such as a car or a train with a rope; would the length of the rope ... A: the length of the rope has no effect on the force you need to pull an object. The only way to reduce ... | |
| Horsepower and acceleration vs weight | 11/20/2005 |
| Q: Kevin I was fiddling with the units trying to come to some conclusions about a project im thinking ... A: the power created by an engine is (theoretically) independent of the car it is built into. So a ... | |
| antimatter | 11/20/2005 |
| Q: I know that antimatter is particles which cancel out ordinary matter.Does an antimatter periodic ... A: Antimatter is very difficult to store, let alone experiment with chemically, since it is annihilated ... | |
| Tire speed | 11/19/2005 |
| Q: I would like to know the answer to a question that a few of us at work were arguing over. If a car ... A: since the bottom of the tire is in contact with the non-moving street, it is not moving (at least ... | |
| weight | 11/16/2005 |
| Q: If you had birds in a box would the box weigh less if some of the birds were flying? If yes, why ... A: The mass of the box and the birds is the same regardless of the actions of the birds. But weight is ... | |
| batteries | 11/16/2005 |
| Q: how big was the firstbattery A: first of all it is not quite clear what is really to be considered the first battery. There is some ... | |
| Uranium | 11/13/2005 |
| Q: Why do we use uranium in nuclear fission and not some other element? A: Uranium is used as fuel in nuclear reactors and in nuclear weapons because it is the only isotope ... | |
| Van de Graaf | 11/10/2005 |
| Q: We have recently been shown a demo of a van der graaf generator. A VDG with one sphere uses the ... A: "Van der Graaf Generator" was a 1970s English progressive rock band. The device you mean is a Van de ... | |
| rough problem | 11/9/2005 |
| Q: I have an extra credit problem that I can't get figured out. I have to convert one formula into ... A: I guess the first equation > Vf=(m1v1i)/(m1+m2) relates the final velocity vf to two masses m1 and ... | |
| Physical Science | 11/9/2005 |
| Q: Which one of these heats up faster glass or wood? A: L., Glass has a greater heat capacity than wood, meaning it takes more energy to raise its ... | |
| Um kites | 11/9/2005 |
| Q: Um i was watching a kite show on t.v. and i found it very interesting. What i was wondering was if ... A: the length of the control line makes a small difference in how the kite handles, but not how it ... | |
| Physics? | 11/8/2005 |
| Q: I'm not sure what to call this stuff that my son is doing..I do know that I can't help him. He ... A: since I don't give out homework solutions out of principle - I only give help, advice or tips for ... | |
| Quantum Field Theory | 11/6/2005 |
| Q: Knowledge level: Layman. What is a quantum field? Do they exist? I've been told two different ... A: Quantum fields do exist. They are measurable. Unfortunately, quantum field theory is a very ... | |
| how ship floats | 11/6/2005 |
| Q: i am a diploma student. i want to know how ship float,on which law, during travelling how they find ... A: an object which has a lower density than water floats on water. Since in a ship there are large ... | |
| kinematics | 11/5/2005 |
| Q: Why do these 2 following problems have intial velocity equalling zero? 1. A baseball pitcher throws ... A: You have to picture the initial conditions of the problems. The ball is resting in the hand of the ... | |
| fundamental frequency | 11/5/2005 |
| Q: if a string resonates to freequencies of 200hz and 250hz but no frequensies in between wont the ... A: the overtones (=second, third etc. harmonic) have frequencies of whole multiples of the fundamental ... | |
| Simple Machines | 11/5/2005 |
| Q: Your drop your lucky dime into a manhole. You take a crowbar to the manhole. If you push on the ... A: Let D1 be the distance from the fulcrum at which the force F1 is applied. And at a distance D2 from ... | |
| gold and electricity | 11/5/2005 |
| Q: the question is "why is gold used in speaker cables?" but i need more in depth knowlegde with ... A: gold is a very good conductor, leading to a low resistance and thus to a high signal quality. And ... | |
| Normal Curve Equivalents | 11/4/2005 |
| Q: What is Normal Curve Equivalents? Thought you might know.. Thanks in advance. Kate A: the normal curve is the graph of the Gaussian distribution, sometimes also called the bell curve ... | |
| kinematics | 11/4/2005 |
| Q: "But v is not 21 m/s but 42 m/s, and then you get 0.43 s." Usually when you have this type of ... A: The ball leaves the hand of the pitcher at 42 m/s, so the starting velocity is not zero but 42 m/s. ... | |
| work done by pressure | 11/3/2005 |
| Q: My question relates to the work done by pressure on a condensed system (solid or liquid). Say you ... A: if the compression is done quickly, then some of the energy does go into increasing the average ... | |
| Physics problem | 11/1/2005 |
| Q: I am a junior in college. We have a physics problem that I can't work out. Can you help? The problem ... A: This problem is a rather complicated extremal value problem. In deriving the distance as a function ... | |
| zero acceleration vs. negative acceleration. | 10/31/2005 |
| Q: Object "A" has a zero velocity. Object "B" has a negative. Which velocity is greater? It has been ... A: you seem to be using the words "velocity" and "acceleration" interchangeably, but in fact they don't ... | |
| intermolecular forces and potential energy | 10/30/2005 |
| Q: For a sample of some substance, internal energy is defined as the sum of three components: ... A: the reference point for potential energy is not at all important (as long as it is used ... | |
| boiling point of liquids and bubble formation | 10/29/2005 |
| Q: In chemistry we are told bubbles will only begin to form when the saturated vapor pressure = ... A: you are right, bubbles at greater depths need a higher saturated vapor pressure to form. But on the ... | |
| kinematics | 10/27/2005 |
| Q: I just started physics a month ago and the following observation has been bothering me for a while. ... A: In your problem the acceleration a is a constant function of time t. a(t) = a This means that the ... | |
| weight | 10/26/2005 |
| Q: If you could somehow get to the center of the earth would your weight be different? A: your suspicion is right. Gravity is a force that attracts masses. If a body is at the center of ... | |
| Nuclear War | 10/26/2005 |
| Q: I'm a university undergraduate in philosophy, however my understanding of physics and science in ... A: That is a complex topic you are inquiring about so I will just answer that only those atoms that are ... | |
| Temperature | 10/26/2005 |
| Q: I want a final temperature of a litter of kool-aid to be 15 degrees. The water coming out of my tap ... A: The desired final temperature lies at two thirds of the difference between the two liquids' ... | |
| history | 10/25/2005 |
| Q: Qu'est-ce qui est un groupe de famille qui ont des ancętre en commun? A: Hallo poop, je ne sais pas le français trčs bien, mais je veux essayer de vous reponder. Je pense ... | |
| angular velocity | 10/24/2005 |
| Q: i have been trying to this problem for a while now. my aprouch was to add angular velocities but did ... A: in questions concerning the dynamics of a system you almost always start from a conserved quantity. ... | |
| junior high science | 10/24/2005 |
| Q: My 7th grade daughter is trying to research and find an answer for her science question of the week. ... A: This experiment was first concucted by the renaissance astronomer, philosopher, and physicist ... | |
| What's beyond Gamma Rays? | 10/24/2005 |
| Q: Kevin: I'm developing a sci-fi plot, in which there's a spaecraft with an AI computer from around ... A: there are no natural phenomena (and yet (?) no artificial sources) that emit radiation that is ... | |
| Physics | 10/24/2005 |
| Q: A high voltage power line carries a current of 110A at a location where Earth's magnetic field had ... A: you need the magnetic force ('Lorentz force') on a current F = l * (i x B) where F is the force ... | |
| Resonant frequency | 10/24/2005 |
| Q: The last time i asked this i got stone-walled by one of your guys because they said it was a ... A: I cannot speak for the other experts (since I don't know them, we are not colleagues, we're ... | |
| A question | 10/23/2005 |
| Q: I am presently doing College Physics, part Two. i have a Question that i have no idea how to ... A: I am missing some essential information from the question. AC or DC? What total voltage (or what ... | |
| energy equation | 10/20/2005 |
| Q: Since the oil crisis, I keep hearing about the e equals mc squared, but what are the units? A: the units are the standardized SI (french: 'systeme international' = international system). The base ... | |
| Density | 10/20/2005 |
| Q: Could astronauts floating in space be explained in terms of density? A: No, astronauts "float" in space because of the (near) absence of gravity far from earth. In the ... | |
| Time-distorting field... | 10/20/2005 |
| Q: I am a writer from Germany and I am currently writing a Fantasy/SF-Story that has to do with ... A: Hallo Eiko Lajcsak, Bei solchen Gedankenexperimenten, bei denen ein Naturgesetz verletzt ist, ist ... | |
| Boyle's Law | 10/19/2005 |
| Q: Kevin- Thank you for your prompt reply. I understand what you've said, but I'm still unsure about ... A: Well, you take some molecules away. The remaining molecules have a larger volume to spread out to ... | |
| Boyle's Law | 10/18/2005 |
| Q: One of the test questions offered by my teacher's guide follows. I'm stumped by the answer the book ... A: A basketball is usually pumped up with a pressure of 6 bar (6 times the atmospheric pressure). The ... | |
| Hi I'm not dealing with... | 10/18/2005 |
| Q: I'm not dealing with physics almost at all I'm rather dealing with literatute so my knowledge of ... A: that is a very broad question, so I would like to refer you to a web site for some reading first. If ... | |
| heron's fountain | 10/17/2005 |
| Q: I am trying to construct a heron's fountain but am having difficulty in getting it to work....As far ... A: Without examining your construction it is hard to guess where the problem lies. I can only make some ... | |
| Nuclear explosion | 10/16/2005 |
| Q: What is the result of exploding a nuclear bomb over water, such as the ocean? Specifically, I would ... A: like any explosion, a nuclear explosion creates a pressure wave and a heat wave. The pressure wave ... | |
| Newtonian vs. Relativity | 10/15/2005 |
| Q: Hey, My name is Scott and I have physics question. Before I begin I want to thank you for the time ... A: There is nothing in relativity that could support, let alone confirm your friend's (creationist?) ... | |
| if an image is inverted does... | 10/14/2005 |
| Q: if an image is inverted does this indicate it is virtual A: What kind of image do you mean? A photo? A digital image? What do you mean by inverted? I can invert ... | |
| Travel faster tha light | 10/14/2005 |
| Q: It is well known that nothing could travel faster than light (C) and also that motion is relative. ... A: the central point of the special theory of relativity by Einstein is that in every inertial system ... | |
| Physics: Finding the frequency | 10/13/2005 |
| Q: ------------------------- Followup To Well heres the question im having trouble with: A floating ... A: since frequency is oscillations per second, your leaf's frequency is 2 Hz (2 Hertz). I still cannot ... | |
| Speed of light | 10/13/2005 |
| Q: I wonder if you could help me with a question that has been puzzling me for some time, if we take ... A: in every reference frame the speed of light is the same constant value. You see the light coming in ... | |
| Physics: Finding the frequency | 10/13/2005 |
| Q: I just started my last two year of high school: home schooling (11th and 12th grade), and Physics is ... A: I am not sure what you mean by "wave frequency of a leaf". Do you mean a leaf on a tree? Do you mean ... | |
| Electricity working in the household | 10/13/2005 |
| Q: We just began the topic of electricity in my Australian 11th Grade physics class. I have some ... A: if devices are to be switched on and off independently of one another, their circuits must be ... | |
| Uncertainty Principle | 10/12/2005 |
| Q: Gday again.. thanks for the quick answer! I've obviously missed the point :) I suspect that the ... A: the radiation beam altering the velocity of the particle observed was indeed the starting point that ... | |
| Science | 10/12/2005 |
| Q: I'm in the 4th grade and my teacher asked us to explaine why--a cup level with water can hold 207 ... A: the effect your teacher has demonstrated is called Surface Tension In physics, surface tension is ... | |
| Uncertainty Principle | 10/12/2005 |
| Q: Gday from Australia! My name is Ben, and I'm a complete layman, and I don't understand the ... A: You will have to broaden your conception of what constitutes a measurement to understand the ... | |
| Candles | 10/11/2005 |
| Q: Do white candles burn faster than colored? I am in 5th grade and I am doing a science fair project ... A: candles are made of diffenent materials (or at least diffenent mixtures of the same materials). This ... | |
| bullet trajectory | 10/11/2005 |
| Q: I am a high school graduate with some college training. My question is why does a bullet, after ... A: a bullet fired from a gun horizontally actually takes a path that is curved downward. This is due ... | |
| vectors- a level | 9/25/2005 |
| Q: the question is if a car travels one complete lap around a circular track at an average speed of ... A: if you only have the average speed v, you cannot deduce any information from that. If in addition ... | |
| free fall | 9/23/2005 |
| Q: A tennis ball is thrown straight up with an initial velocity of +22.5 m/s. It is caught at the same ... A: the free fall can be a "normal" fall starting at zero velocity and hence only moving downward, or it ... | |
| High School Physics - acceleration/velocity | 9/23/2005 |
| Q: I am trying to re-draw a graph that I received in the form of a drawing as distance versus time by ... A: Velocity is distance difference divided by time difference: v(t) = ( d2 - d1 ) / ( t2 - t1 ) So for ... | |
| velocity vs. acceleration | 9/22/2005 |
| Q: I hope I'm finding you in the best of health. I have great difficulty answering velocity and ... A: there are two special cases of motion that are usually treated as models in textbooks and in ... | |
| Water Buoyancy Calculations | 9/20/2005 |
| Q: I'm a fellow "AllExperts Expert" in the realm of computers, so if you have any questions - I'd be ... A: The buoyancy of an object in water is exactly the same force as the weight of the displaced water. ... | |
| Double slits experiments | 9/18/2005 |
| Q: I am uni yr 1 engineering student. My question is as below. Two 0.01mm wide slits are located 0.03mm ... A: I too interpret both questions as asking fot the same value. In a sinusoidal pattern the distance ... | |
| atom | 9/17/2005 |
| Q: Very interesting. I saw a 1" thick piece of glass that was perfectly clear as air. Does that mean ... A: Glass is an amorphous solid, created by cooling down liquid silicon dioxide (the same substance sand ... | |
| rain dynamics | 9/16/2005 |
| Q: why the rain drops fell angularly like this //////////// when arrording to gravitation they ... A: there are two forces acting upon the raindrops: Gravity and the wind. Gravity alone would make the ... | |
| couple puzzlers for me | 9/14/2005 |
| Q: Nice service - I have a couple of questions/observations that have baffled me and I thought I might ... A: 1) Helium does have a mass, although its density is smaller than air at the same pressure. This is ... | |
| Parakinesis | 9/14/2005 |
| Q: 9/14/05 3:24 PM Hello: I hope I'm asking the right person but: What is parakinesis, and how does ... A: I know two different meanings of parakinesis, both of which are not in my area of expertise, but I ... | |
| Tornado's and physical science | 9/9/2005 |
| Q: What i meant to ask i kno it didnt sounds like a good question But i need Information on How are ... A: tornados are a subject for study by the physical sciences. Especially physics, geophysics and ... | |
| duality, math for relativity | 9/8/2005 |
| Q: Can you explain particle/wave duality to me? I'm a college student studying math-biology with a year ... A: I don't know how to answer to a problem that cannot be solved by reading several books by this ... | |
| Logic Of The Science | 9/4/2005 |
| Q: I say , " The meaning of energy is depended on the meaning of mass ? " and I believe it's a ... A: I don't quite understand what your quote means, "the meaning of energy" and "the meaning of mass" ... | |
| Science | 9/1/2005 |
| Q: What is the difference between quantitative data and qualitative data? Anf if possible, do you know ... A: In statistics, qualitative analysis consists of procedures that use only dichotomous data – that is, ... | |
| relitivistic energy | 8/29/2005 |
| Q: Hey I'm confusioned, or need clarification on the theory of relitivity. I live in scotland, and when ... A: first of all, if you travel towards a piper at a constant speed then the sound is affected by the so ... | |
| Electricity & Water Q's | 8/27/2005 |
| Q: Thanx for the answer, but i have some other questions... 1. Most sites i have been to say that ... A: Hell Zed, distilled water (or pure water) has no contaminations (mainly salts) that make the water ... | |
| stability of matter & energy | 8/25/2005 |
| Q: I want to know if the theory of "the Stability of ..." is referring to the matter & energy in ... A: the theory means matter or energy was not created *in the scope of validity of the theory*. If ... | |
| Do you lose energy in water? | 8/25/2005 |
| Q: If you attach a 9v battery to a pipe of saltwater and connected it to a voltmeter do you lose ... A: ideally the battery should not lose energy, because the electric circuit is not completed. The ... | |
| Through how thick matter x-rays... | 8/22/2005 |
| Q: Through how thick matter x-rays can pass (it is clear, that it pass less through the harder matters ... A: Like all electromagnetic rays, X-rays can either pass through matter, be scattered when hitting ... | |
| Archimedes Principal | 8/22/2005 |
| Q: This HAS BEEN a homework assignment but I have done it and had it marked but do not understand the ... A: The brick in the boat displaces a mass of water equal to its own mass. The submerged brick displaces ... | |
| Water Volume during Great Flood | 8/22/2005 |
| Q: Kevin, my knowledge level on this is almost minimal. The thought has come up about the volume of ... A: The earth has a radius of approx. R=6374 km. Its surface area is thus A= 4*Pi*R˛ = 5.1 *10^14 m˛. ... | |
| Pressure Density and Temperature in a Gas | 8/20/2005 |
| Q: Why is hot air less dense than cold air? I know it is because the molecules are more separated in a ... A: if you heat a fixed amount of gas it either expands (increasing its volume, thus decreasing its ... | |
| Slow Neutron Capture | 8/18/2005 |
| Q: I don’t quite understand why in nuclear physics slow, thermal neutrons are easier for the nucleus ... A: Schroeter, The explanation of why thermal neutrons are more easily captured than high energy ... | |
| physics | 8/18/2005 |
| Q: 1) what is the origin of gravitational force? 2) if an object is in space what forces implies on ... A: the gravitational force acts on all masses and is proportional to the sum of the masses involved. ... | |
| The speed of light........ | 8/15/2005 |
| Q: I'm not sure whether you can help but here goes anyway. A work colleague sent me the following ... A: > What do you think would happen to your shadow now that you > are faster than the speed of light? ... | |
| Creationism | 8/14/2005 |
| Q: I believe that I read somewhere that there is a law of physics which states that, in the natural ... A: It is true that the laws of physics, which are the laws scientists have found to govern the ... | |
| warm vs cold | 8/13/2005 |
| Q: What is the difference between cold milk and warm milk - or any other liquid or matter for that ... A: if there is no chemical reaction triggered by the heating, then the difference between a cold liquid ... | |
| Through what materials the... | 8/10/2005 |
| Q: Through what materials the infrared waves pass? Can they pass through plastics (and how thick)and ... A: Infrared waves are electromagnetic waves that have a wavelength longer than visible light, but ... | |
| Ram Implosion Wing and Quantum Gravitics | 8/9/2005 |
| Q: I am writing because I am trying to understand some of the more complex systems and theories behind ... A: I have just briefly scanned the pages you linked, so my opinion is just tentative. But I do not ... | |
| physics | 8/8/2005 |
| Q: What gases or combination of gases exhibit magnetostrictive characteristics? A: the pheonomenon of magnetostriction can only occur in ferromagnetic substances. Ferromagnetism can ... | |
| energy in an atom of hydrogen | 8/5/2005 |
| Q: is it possible to calculate the energy in a single atom of, say, hydrogen if completely converted to ... A: The speed of light is approx. 300 000 km/s One hydrogen atom has a mass of 1.00794 u (atomic units) ... | |
| energy in an atom of hydrogen | 8/5/2005 |
| Q: is it possible to calculate the energy in a single atom of, say, hydrogen if completely converted to ... A: the answer to your question is simply: yes. To set the energy free (to convert it to another form ... | |
| temperature measurements | 7/13/2005 |
| Q: i am wilson by name an ex student ofa secondary school. when i was reading my physics textbook,i ... A: a body emits radiation (mainly heat radiation) of a characteristic profile. The intensity ... | |
| calculating power (kcal/hr) | 7/12/2005 |
| Q: I wanted to know how to calculate the Power (kcal/hr) is there an equation to calculate it? I only ... A: There are two different processes that you want to hold apart: 1) Calculating power: Power p is ... | |
| Special Relativity / E&M | 7/11/2005 |
| Q: I am a university student who recently switched to physics. I have a decent background in classical ... A: for your first qustion I want to give you the short answer and say: Both are correct and it is no ... | |
| time | 7/10/2005 |
| Q: I am wondering how there can be a set amount of time (planks constant)? - I thought that time was ... A: People also thought that mass was divisible forever, until it was discovered that it comes in quanta ... | |
| Lasers and colored light | 7/6/2005 |
| Q: What are the chemical and physical properties of: red lasers orange lasers yellow lasers green ... A: lasers are monochromatic (one-colored) and since white light is the mixture of light of all colors, ... | |
| thermometry | 7/4/2005 |
| Q: at what temperature have the centigrade and fahrenheit readings the same numerical value? please ... A: You can convert the units using the following rules (equations): [°C] = ([°F] ? 32) · 5/9 [°F] = ... | |
| Strange solid shape | 6/29/2005 |
| Q: There were no math expert on this site but maybe you can help. I once at UCBerkeley in 1964 came ... A: The easiest way to construct a polyhedron with seven faces is a five-sided prism. It consists of two ... | |
| sound | 6/24/2005 |
| Q: a wave with a period of 0.008 second has a frequency of? A: frequency f is related to period T by f=1/T Plug in your value and evaluate. Side note: Period is ... | |
| PHYSICS | 6/24/2005 |
| Q: I'm stuck on this problem, I am not looking for the answer, I want to learn how to do it. I just ... A: You will need the specific heat capacity of copper. Look here for an explanation and a value: ... | |
| Relationship between temp and pressure | 6/24/2005 |
| Q: Kevin. That actually made good sense. In my case, I'm not concerned with HOW the pressure is ... A: You can easily cool a gas, but since it has a heat capacity of around 1/1000th of the heat capacity ... | |
| Relationship between temp and pressure | 6/23/2005 |
| Q: I was an A student in college physics ... 20 years ago! I know there is a relationship between ... A: there are several gas laws. The laws include Boyle's law, Charles's law, Gay-Lussac's law, Graham's ... | |
| Fractals and the space-time continuum | 6/23/2005 |
| Q: ..This may sound a little bizarre, but I am an actress preparing for an audition. I am trying to ... A: (I will only use two very easy equations for the sake of illustration.) In mathematics, a ... | |
| boiling water | 6/21/2005 |
| Q: Kevin, for your interesting answer. Tell me ,please, are these gases present in all kinds of water? ... A: how much of a certain gas is dissolved in a liquid depends on how much the liquid was exposed to the ... | |
| work-energy principle in different reference frames | 6/21/2005 |
| Q: I understand that the extra amount of work is due to the initial velocity measured in the second ... A: In your example you have not (yet) examined the whole picture: A force always has a cause. This ... | |
| boiling water | 6/19/2005 |
| Q: I'm 26 years old , and I'd like to know,please ,what exactly happens, physically speaking, when ... A: If you give water more and more (thermal) energy, the water moleculed move faster and faster. At a ... | |
| Quantum wave function | 6/17/2005 |
| Q: level: BSEE In the quantum world, the results you get from a measurement are based on the ... A: your question indeed goes towards the foundations and interpretations of quatum mechanics. This is a ... | |
| temperature and thermodynamics | 6/17/2005 |
| Q: I am a university student taking advanced university physics with a limited calculus background (i'm ... A: Let me start with some definitions: An algebraic function is a function that can be constructed ... | |
| work-energy principle in different reference frames | 6/17/2005 |
| Q: Is work_energy principle valid in all inertia reference frames with different speeds? For example, ... A: In the moving reference frame the object travels 60m (the 50m it travels in the resting reference ... | |
| Photons and Virtual Photons. | 6/15/2005 |
| Q: Is the photon the messenger particle of the electric charge in a wire and in a vacuum? And is the ... A: a photon is the quantum of the electromagnetic field. It always moves at the speed of light. ... | |
| The effect of the length of the period of a rigid rod pedulum | 6/15/2005 |
| Q: I would like to know whether varying the length of a rigid rod pendulum changes the speed it swings ... A: > I would like to know whether varying the length of a rigid rod pendulum > changes the speed it ... | |
| Photons and Virtual Photons. | 6/14/2005 |
| Q: Level: BSEE When electricity travels down an ideal long line it moves at the speed of light. What is ... A: electricity is the flow of charged particles (usually electrons) in a conductor. The electromagnetic ... | |
| radiation | 6/13/2005 |
| Q: Q1 what does alfa-beta and gama mean in radiation terms A: alpha radiation is radiation consisting of particles made of 2 protons and 2 neutrons, components of ... | |
| electricity voltage | 6/13/2005 |
| Q: Q1 why is electricity set at high voltage Q2 what is national grid and how it works A: > Q1 why is electricity set at high voltage 'High voltage' is usually defined as voltage greater ... | |
| electric field strength | 6/12/2005 |
| Q: . I'm working through your answer, and have a few questions the answers to which might help me think ... A: 1. I couldn't find a relevant definition of homogenous. Am I correct to assume that a “homogenously ... | |
| electricity and magnetism | 6/10/2005 |
| Q: I'm a 5th grade sci. teacher without an answer: I've taught my students that electricity, a form of ... A: the electrons just go around in a circle in the conducting circuit. For every piece of wire there ... | |
| PET | 6/10/2005 |
| Q: What difference between the Positron Emission Tomography and the Single Photon Emission tomography? A: both methods require the patient to be injected with a radioactive substance. For the PET the ... | |
| Flash after going into warp | 6/9/2005 |
| Q: I understand that the "warp drive" used in many science fiction movies, such as Star Trek, is ... A: the warp flash is a television invention to make it look more spectacular. I read that the technical ... | |
| electricity and magnetism | 6/8/2005 |
| Q: I'm a 5th grade sci. teacher without an answer: I've taught my students that electricity, a form of ... A: the electrons are in the wire already. This is the case in every conducting material. In order to ... | |
| electric field strength | 6/8/2005 |
| Q: I have a question on electric field strength. (But first, my non-homework disclaimer: This is not a ... A: the electric field of one homogenously charged plate can be calculated from Gauss' law (remember the ... | |
| kinematics problems | 6/3/2005 |
| Q: i just want to know how to set up a problem, it asks to calculate a car's average acceleration and ... A: acceleration a is the change rate of velocity v per time t: a = v / t So you already have all the ... | |
| gravity | 6/2/2005 |
| Q: every object has gravity-so why is the earth not attracted to us as we are to it?what 2 factors ... A: the earth is indeed attracted to us, and with the same force that we are attracted to the earth. The ... | |
| magnifying lens | 5/31/2005 |
| Q: Is there such a thing as a magnifying lens that can be placed directly on the surface to be ... A: the reading/magnifying device you are probably thinking of is very convex on one side and planar on ... | |
| picoamps and millivolts | 5/31/2005 |
| Q: I am looking for the relationship between picoamps and millivolt. I mean if I have a reading of ... A: the prefix 'pico' means a billionth of a billionth, the prefix 'milli' means a thousandth. Now for ... | |
| Lowest Frequency | 5/31/2005 |
| Q: I just have a simple question that may initiate more. I am about 4 years out of High School with not ... A: according to quantum theory, energy only comes in quanta ("chunks" of a certain magnitude). But this ... | |
| refracting light | 5/31/2005 |
| Q: Simple question really, if light is refracted when travelling through a material such as water, i ... A: the vacuum speed of light is c ~ 300 000 km/s. In a medium (e.g. water) light travels at a different ... | |
| physics books | 5/28/2005 |
| Q: i want to self teach myself physics. and looking for good suggestions on which books or set to buy. ... A: I mainly work with college and university textbooks. Of these I can recommend Halliday, Resnick: ... | |
| conversion units | 5/26/2005 |
| Q: A house is 50.0 ft long and 39.0 ft wide, and has 8.0-ft-high ceilings. What is the volume of the ... A: To convert from ft to m use the following: 1 ft = 0.3048 m So e.g. 50 ft = 50 * 0.3048 m You can ... | |
| Speed of Light Constant? | 5/22/2005 |
| Q: Knowledge Level - BA Humanities in Philosophy with a keen interest in science. The shortest ... A: Einstein said that light always moves along a straight line through space-time. He also said that ... | |
| Gyrostat | 5/17/2005 |
| Q: Since a gyrostat resist any change in the orientation of it's axis of rotation, therefore I need to ... A: If you exert a torque on a gyrostat then you change its total angular momentum. If you apply this ... | |
| Planitary Motion | 5/14/2005 |
| Q: How can you find the velocity of the moon, which follows the path of a hypotrochoid, relative to ... A: since the velocitiy of B in the system of stationary A and the velocity of C in the system of ... | |
| The Earth, rotation, and gravity | 5/11/2005 |
| Q: sir. I wonder if you might have some ideas around how I might explain, to an inquisitive ... A: "How come, if the Earth spins, we don't fall off it? To answer this question you will have to ... | |
| charge | 5/9/2005 |
| Q: I have a simple question. What really IS 'charge'? I know a electron has negative charge and a ... A: charge is a property of elementary particles like electrons, protons, positrons and several more ... | |
| Ice Cubes | 5/9/2005 |
| Q: Does hot water freeze faster than cold water? If it does, why? A: > Does hot water freeze faster than cold water? If it does, why? of course hot water takes longer ... | |
| Speed of Light | 5/8/2005 |
| Q: Sir, I know that if you spin a beacon of light fast enough, the beam, at a few billion kilometers, ... A: if you are thinking of the beam of light like you are thinking about e.g. a sword, then this will ... | |
| speed of light | 5/4/2005 |
| Q: This is a 2 part question. First when was the speed of light first measured and how was it done. ... A: For your question may I refer you to ... | |
| Physics, speed of a falling object | 5/3/2005 |
| Q: I would like to know how fast something is going when it hits the ground in mph. Can I get a ... A: the acceleration a of an object falling at the surface of the earth is 9.81 m/s^2. So its velocity v ... | |
| legrange points | 5/2/2005 |
| Q: my understanding is that legrange points refer to unstable and stable points of gravitation around ... A: You can read a lot about Lagrange points here: http://en.wikipedia.org/wiki/Lagrange_points This ... | |
| a question | 4/24/2005 |
| Q: How are you? I have a question here , ,i cannot even decide which formula to use so you can imagine ... A: you wrote: The steering wheel of a car has a radius of 0.326m. The same forceis applied in the same ... | |
| Physics and Baseball | 4/24/2005 |
| Q: Is it possible to use Physics to determine exactly how far a batter will hit a ball in baseball ... A: If you know all variables (pitch speed, direction, curl, bat speed, wind speed, etc.) exactly, then ... | |
| space | 4/19/2005 |
| Q: Hey. I was just wondering how a spacecraft is able to propell itself through space? Obviously on ... A: the rocket motor does not need a substance to push against in order to propel the vehicle forward - ... | |
| Planck's Units | 4/18/2005 |
| Q: 1.Is the planck's length defined as the sqrt. of Planck area or is the Planck area defined as the ... A: 1. Planck area is derived from Planck length (Planck length squared). Max Planck wished to create ... | |
| earths magnetic field | 4/15/2005 |
| Q: I have asked you questions before regarding chemistry and physics. This may not be your fortay, but ... A: If the earth's magnetic field collapsed, the so called "sun wind", a stream of ionizing particles ... | |
| bending of space | 4/14/2005 |
| Q: I was wondering what the "bending" of SPACE mentioned in relativity due to gravity means? I thought ... A: Space and time are difficult concepts, because they are abstract and the framework itself in which ... | |
| Light my fire | 4/14/2005 |
| Q: What started out as an innocent question from a five year old has continued to intrude upon my daily ... A: Fire is a chemical reaction called oxidation, between a fuel (some carbon compound) and oxygen. The ... | |
| Wheatstone Bridge | 4/14/2005 |
| Q: How does the Wheatstone Bridge function and why does it behave this way? Is their a way that ... A: The principle of a Wheatstone bridge is neatly explained here: ... | |
| general physics | 4/12/2005 |
| Q: How are you doin. By the way what is "eggdrop competition"? Anyway i have a physics question that i ... A: the eggdrop competition seems to be a competition held at schools all over the US where the object ... | |
| physics | 4/12/2005 |
| Q: does the weight of an object have anything to do with how fast it falls. example, if i drop a 5 ... A: if one neglects friction with the air then the mass of an object has no influence on the dynamics of ... | |
| black colour of umbrella | 4/12/2005 |
| Q: I am an engineer by profession I have a practical question to ask. as for as I know, Black body when ... A: The term "black body" in physics usually refers to an ideally black surface, which is most closely ... | |
| Simple harmonic motion | 4/11/2005 |
| Q: assumption:earth is a perfect sphere a cylindrical tunnel is dug from the surface through the centre ... A: a harmonic motion requires a force that is directly proportional to the amplitude of the moving body ... | |
| paraparticles, and subatomic particles | 4/11/2005 |
| Q: What is paraparticles, and positronium, and their chemical and physical properties? Does ... A: All matter consists of atoms. These atoms form molecules or crystalline structures held together by ... | |
| the leaves | 4/9/2005 |
| Q: i am a grade 6 student, i have a question what does the plants have to be able to turn co2 to o2? ... A: Plants have a chemical called chlorophyll, which is also responsible for the leaves' green colour. ... | |
| pressure/temp | 4/7/2005 |
| Q: What will happen to a glass of water if placed on the surface of moon on dayside and nightside of ... A: While the force of gravity on the moon is smaller than what one would feel here on earth (an ... | |
| free falling | 4/6/2005 |
| Q: I am trying to find out what is the maximum velocity at which an object will free fall…assuming no ... A: > I am trying to find out what is the maximum velocity at > which an object will free fall…assuming ... | |
| Sound and Light | 4/5/2005 |
| Q: Which has the faster speed between Sound and Light. If the sound has faster speed than light then ... A: Sound travels at approx. 333 m/s and light at nearly 300 000 km/s. This is why you first see a ... | |
| Work and Energy | 4/4/2005 |
| Q: Is work being done when someone coasts downhill on a bike? A: work is force times distance. The force of gravity works on the biker for the distance he coasts, ... | |
| Proving times relation to gravity | 4/4/2005 |
| Q: Time after time physicists claim that experiments have been made to prove that time goes slower the ... A: The experiments you mentioned have been conducted, cf. http://physicsweb.org/articles/world/18/1/5/1 ... | |
| ice and heat | 3/29/2005 |
| Q: 11 years old Question if I place several ice in a cup in a open room, then i placed a termometer ... A: The best way to find out what happens if you do this or that is to do it and find it out (unless it ... | |
| Some thing different | 3/28/2005 |
| Q: Sir, I am sorry to say that the question I am about to ask concerns mathematics(I found no ... A: There is no official court of mathematics. Results and findings are published in journals and ... | |
| physics, photo electric effect | 3/27/2005 |
| Q: how is linear momentum conserved in photo electric effect ? A: the photon carries a momentum which it transfers to the atom. The atom then emits an electron, also ... | |
| Deformation Physics | 2/28/2005 |
| Q: I'm trying to put together a computer simulation of objects breaking. I'm stuck on the collision ... A: You need to solve the equations for energy and momentum. The sum of all momenta before the ... | |
| Periodic table | 2/27/2005 |
| Q: Kevin, could you tell me why the Periodic Table is like a map of the elements? A: The periodic tabele lists all elements in a table where the atomic properties of elements in the ... | |
| circuits | 2/27/2005 |
| Q: Ok I have got a circuit with three cells cell 1 has an emf of 6v and a internal ressistance of 2 ... A: if you already have the potential at the points then calculating the potential difference between ... | |
| Bohr model of the atom | 2/24/2005 |
| Q: Kevin, Can you explain to me why the absorption lines in the spectrum of Hydrogen have the same ... A: The absorption and emission lines of atoms have exactly the same wavelengths. Wavelength of a photon ... | |
| Newtonian vs. Quantum mechanics | 2/24/2005 |
| Q: Kevin, Why has quantum mechanics replaced Newtonian mechanics in describing the subatomic and atomic ... A: At the length scale of atoms the effect that energy is quantized must be taken into account whereas ... | |
| The nature of sound | 2/23/2005 |
| Q: I was wondering if you would please be able to tell me the fundamental nature of sound, ie, what ... A: You wrote: If sound is the fluctuations around/by matter could it be that a vacuum is simply the ... | |
| Friction | 2/23/2005 |
| Q: I am in a general physics algebra based class and I also took one year of physics in high school. I ... A: I read your second question now and I think you are looking for the coefficient for kinetic ... | |
| Light | 2/23/2005 |
| Q: Respected Sir, Sallam, Sir my question from you is this: "The speed of ... A: the speed of light can be measured in various different ways. They are too numerous and complicated ... | |
| Planck's constant | 2/22/2005 |
| Q: If Plank's constant were smaller would quantom phenomena be more or less conspicuos than they are ... A: Energy is quantized in units of Planck's constant. This quantization is the origin of quantum ... | |
| Current | 2/22/2005 |
| Q: Respected and one of my favourites, Sir I have asked from u a question relating to the AC and DC ... A: Even in DC the current is not the transport of single electrons from one pole to the other. At the ... | |
| Differences in hot and cold water | 2/22/2005 |
| Q: I am in 6th grade. I recently did an experiment with hot and cold water and cotton balls. The cotton ... A: this is in reply to the question Gracie asked me via allexperts.com Hello Gracie, I am not sure ... | |
| The nature of sound | 2/21/2005 |
| Q: I was wondering if you would please be able to tell me the fundamental nature of sound, ie, what ... A: Matter and energy (which are equivalent to each other, E=mc^2) are the fundamental building blocks ... | |
| subtance compound | 2/21/2005 |
| Q: are collids mixtures A: colloids are an intermediate between solutions and suspensions (the latter may be called a ... | |
| The nature of sound | 2/21/2005 |
| Q: I was wondering if you would please be able to tell me the fundamental nature of sound, ie, what ... A: sound is a wave in matter, i.e. density fluctuations in a gas, fluctuations of atomic distances in a ... | |
| Current | 2/20/2005 |
| Q: Since in direct current, the current flows in one direction, on the other hand, in AC current the ... A: In direct current (DC) the current flows in one direction, that means that the charges (electrons) ... | |
| Acceleration | 2/18/2005 |
| Q: I have a simple question, using the "it is easier to ask than look it up" rule... What formula ... A: > "it is easier to ask than look it up" (you would learn more if you looked it up, but that's your ... | |
| LASER | 2/17/2005 |
| Q: what is a laser ?what are the applications? thank you A: A 'normal' light source like the sun or a light bulb emits photons in all directions and the photons ... | |
| Hydrogen spectrum lines | 2/16/2005 |
| Q: Why would a hydrogen spectrum contain many lines even though H atom has only a single electron? ... A: the electrons (even the single electron of a hydrogen atom) can inhabit different states in the ... | |
| If you drop a rock down a... | 2/13/2005 |
| Q: If you drop a rock down a hole that went through the center of the earth, excluding heat, what would ... A: if you exclude friction, then the rock would accelerate until it reaches the center of the earth. ... | |
| sound | 2/13/2005 |
| Q: My son built something called a popper by taping a square made of copy paper to a larger triangle ... A: The popper is opened by the air resistance. The parts that fold out are accelerated until they reach ... | |
| Quantum physics - relativity | 2/12/2005 |
| Q: I have no qualifications in physics but am interested in quantum field theory and relativity - I ... A: In your example with the ball on the rope you cannot apply special relativity theory straightforward ... | |
| steam | 2/12/2005 |
| Q: How does steam give up energy, is it by condensation? How does it turn turbines? Thank you Jerome A: when you boil water to generate steam the mass expands or (if it cannot expand) it builds up ... | |
| electrical spark phenomena | 2/10/2005 |
| Q: There are several electrical spark phenomena; lightning, electric arc light (also called klieg ... A: Sparks are electrons flowing from one charged body to another oppositely charged (or neutral) body. ... | |
| Areas of study | 2/8/2005 |
| Q: I am aspiring to become a physicist and to study for my Ph.D. I understand the amount of math that ... A: I don't know the English or American university system so well, since I live in Germany. I will just ... | |
| Potential divider/potential difference | 2/8/2005 |
| Q: I have been studying general physics for 3 years now. In a potential divider why does the larger ... A: > V varies directly with R. > But why does this happen? Two identical resistors in a series have ... | |
| particles | 2/7/2005 |
| Q: Kevin, Do you know what kind of particle is emitted when a carbon isotope 14/6 C decays into the ... A: 14/6 C has 6 protons and 8 neutrons in the nucleus. One neutron decays into a proton, resulting in a ... | |
| gravity, mass, friction | 2/7/2005 |
| Q: For someone weighing say 165lb. how much pressure would it take to run up a stucco wall say 10ft ... A: I don't quite understand what kind of pressure you are referring to in your question. If you are ... | |
| what type of science is "can... | 2/3/2005 |
| Q: what type of science is "can people identify food with their senses" under? A: if it is an investigation of the physical capabilities of the human body (i.e. how fine are the ... | |
| My son's science fair project | 2/2/2005 |
| Q: My son is working on his science fair project. He is 11. What he and his teacher have decided, is ... A: I don't live in the US, so I don't know how science fair projects are handled, but I think it should ... | |
| Atmospheric pressure/ water pressure | 2/1/2005 |
| Q: I am in fourth grade and doing the Science Fair. I'm wondering if atmospheric pressure affects water ... A: water is (almost) incompressible, so unlike gas it does not have a pressure that characterises its ... | |
| higgs boson | 1/31/2005 |
| Q: What are the likely practical applications from the discovery of the Higgs Boson? I read that CERN ... A: The discovery of the Higgs boson is not at all likely to have any direct "practical applications" if ... | |
| ice shape and melting | 1/30/2005 |
| Q: and won the science fair for my grade at my school. my project question was "how does the shape of ... A: Remark: Your project question was probably how the shape of ice *a*ffects (not effects) the rate at ... | |
| special relativity | 1/29/2005 |
| Q: BTW, that URL you suggested looks like a *fabulous* resource for me, so extra thanks for that! I ... A: >I want to make sure that I know what a "reference frame" >is. Would I be correct to describe it as ... | |
| Einstein's theories | 1/27/2005 |
| Q: I've read about Einstien's theories of Relativity in very simple terms (Steven Hawking's "the ... A: Einstein is most famous for his theory of relativity, but he has ahieved groundbreaking advances in ... | |
| special relativity | 1/27/2005 |
| Q: My first-year physics college text states that special relativity deals only with inertial reference ... A: The inertial frames of reference are all related by the Lorentz transformation, which transforms ... | |
| Wavelenght | 1/27/2005 |
| Q: Does increasing the frequency of a wave also increase its wavelenght? How are these quantities ... A: ordinarily the frequency f and the wavelenghth l are related via the velocity v with which the wave ... | |
| Resonating in sympathy | 1/26/2005 |
| Q: I'm a violin student who has also been studying physics. I've noticed this effect on the violin when ... A: when sound waves hit an object, this object will resonate, that is take up the vibratation of the ... | |
| energy | 1/25/2005 |
| Q: Does every stationary body possess potential energy? A: A body (it need not be stationary) posesses potential energy only in a force field that is the ... | |
| Mass and weight | 1/24/2005 |
| Q: Question - If you make a hole to the center of the earth and drop a stone in it. How do the mass and ... A: Mass is a property of matter that is independent of its location. It is measured in kilogram [kg]. A ... | |
| Gravity | 1/23/2005 |
| Q: Can anything ever have a downward acceleration greater than g? If so, how can this be accompished? A: just add any kind of propulsion system (a motor, a jet, a rocket, a spring, ...) that adds a ... | |
| How can we measure the speed of light? | 1/23/2005 |
| Q: Kevin Johnson, I have recently read a book by KIP S. THORN with the title "Black Holes and Times ... A: Bonjour Rémi, Mon francais n'est pas bien, aber ich könnte auf Deutsch antworten.Well the question ... | |
| Viscosity and boiling point | 1/22/2005 |
| Q: If I am trying to find out if viscosity affects boiling points, maybe I should use 3 different ... A: That is a good idea to use different liquids instead of a liquid compared to a suspension. Different ... | |
| e=mc2 | 1/22/2005 |
| Q: There have been several TV programs recently about Einstein and relativity but none have explained ... A: You are right, light does travel at different speeds through different media. What is meant by ... | |
| x-ray radiation | 1/20/2005 |
| Q: Kevin. I'm also an expert volunteer here (grad school admissions and meditation). My dentist says ... A: The harmfulness of radiation is not only dependant on the total energy absorbed by the body, but as ... | |
| Viscosity and boiling point | 1/20/2005 |
| Q: I am 10 years old. Why does a thicker liquid (4 cups water with 2 cups flour dissloved in it) boil ... A: First of all, if you mix flour with water, technically speaking you don't get a solution, but ... | |
| gravity | 1/18/2005 |
| Q: why can you place a cylinder of 20 gal.of water on one side of a balance beam & a cyl. of 1 gal. of ... A: with a balance you compare weight, with the communicating pipes you compare pressure. Weight is ... | |
| About your career | 1/18/2005 |
| Q: I was just a bit curious of your profession as well as many other physicists in other fields.I ... A: my experience may not be so relevant for you, as I have lived in Germany all my life so far and the ... | |
| Action/reaction pair. | 1/16/2005 |
| Q: You are incorrect, Kevin. Here is the truth: 1. When you exert a force through your toes against ... A: First of all: I don't appreciate your tone and your overconfidence. You are the questioner asking ... | |
| Action/reaction pair. | 1/16/2005 |
| Q: How does the earth push back on you when you exert a force on it (action-reaction pair of forces in ... A: Every force generates an opposing force of the same strength in the opposite direction. This is ... | |
| hardcore unification | 1/15/2005 |
| Q: sir, i'd like you to see the section harcore unification on this page: www.geocities.com/dedaNoe and ... A: I don't know what you mean when you think you "did it". The relevance and meaning in this context ... | |
| Torque and Angular Acceleration | 1/14/2005 |
| Q: I am currently an undergraduate student in need of help with homework. TheThe seesaw is pivoted in ... A: the bar's mass is not at the same position as m_2. It is distributed homogenously along the distance ... | |
| Motion | 1/14/2005 |
| Q: I know it effect it by how much A car with the mass of 200 kg is moving (no friction) on a horiz ... A: your question sounds like a homework problem and I normally don't do homework solutions. But I will ... | |
| Question?... | 1/13/2005 |
| Q: I'm a college student and two of my friends are in disagreement about a hypothetical situation. It ... A: If you disregard the fact that the suspension dampens the impact of the car that is dropped, then ... | |
| conductivity | 1/13/2005 |
| Q: Sir, Would you please explain what conductivity is? Thank You, Phillip. A: Electrical conductivity is a measure of how well a material accommodates the transport of electric ... | |
| houses and lines | 1/12/2005 |
| Q: There are three houses, a, b, and c. These houses need to be connected to water, w, sewer, s, and ... A: the answer to the mathematical version of this problem is: There is no solution. In case you are ... | |
| waves | 1/12/2005 |
| Q: what is the relation between particle velocity(frequency) and wave velocity(frequency)? A: I cannot guess your knowledge level, and you did't tell me, but judging from the question I presume ... | |
| Quantum Physics | 1/10/2005 |
| Q: I'm trying to write a book defending science from mysticism - a pointless task, but still - and have ... A: > a book defending science from mysticism - a pointless task, but still Not at all pointless. I see ... | |
| work | 1/10/2005 |
| Q: This is what I came up with, am I close. I dont understand the word over (is it a divsion prob or ... A: > is this correct > Answers ? > 630.013 Yes, 630.013 J is correct. >I dont understand the word ... | |
| Physics | 1/10/2005 |
| Q: Why is replusion the only sure test that a metal bar is a magnet? A: the only sure test that a metal bar is a permanent magnet is repulsion because metals can be ... | |
| gravitation | 1/10/2005 |
| Q: I AM A GCE A LEVEL STUDENT.I WILL BE VERY GRATEFUL TO YOU IF YOU WILL HELP ME TO SOLVE MY SOME ... A: Your questions were: I AM A GCE A LEVEL STUDENT.I WILL BE VERY GRATEFUL TO YOU IF YOU WILL HELP ME ... | |
| work | 1/9/2005 |
| Q: I am coming up with different answers Grav=9.81 Wieght=6.8kg mass dent = 66.708 lenght=30.48 ... A: It seems your mass density is not converted correctly to the metric unit kg/m= 0.45359237* 0.3048 ... | |
| Relativity | 1/9/2005 |
| Q: I am a teacher, not in Science, although I have a general understanding of Relativity. Some time ago ... A: Your answer is exactly on spot: Since there is no absolute time in relativity theory, i.e. time is ... | |
| If changed it'll affect to astrology? | 1/9/2005 |
| Q: If changed it'll affect to astrology? Question Happy new year! I heard, Earthquake that happened ... A: the changes in the earth as a result of the earthquake are measurable. The locations of some islands ... | |
| Series circuit | 1/8/2005 |
| Q: I did an practical experiment in my school. The experiment was to make a series circuit with three ... A: If three identical light bulbs are in a series circuit, then ideally the potential difference over ... | |
| work | 1/8/2005 |
| Q: I know how to figure work, however as the chain is pulled up it gets lighter. I cant figure this. A ... A: You will have to integrate the mass density of the chain (15lb/ft) times the earth's gravitational ... | |
| Black Hole | 1/7/2005 |
| Q: If a blackhole is created when the escape velocity is greater than lightspeed, than why is it that ... A: the theoretically calculated escape velocity (needed to overcome the gravitational field) of a black ... | |
| how small can anything be? | 1/7/2005 |
| Q: my question is, HOW SMALL CAN AN OBJECT GET? When you take into account that in theory you can ... A: The answer to your question depends on what you would count as an object. By cutting with more and ... | |
| Particle Accelerators and the Planck scale. | 1/6/2005 |
| Q: As I understand it, particle accelerators are basically particle creators. Take a bunch of protons ... A: I am also curious how close we will get to the energy scale of the big bang in the future. There are ... | |
| Tsunami | 1/5/2005 |
| Q: Kevin, I heard that one of the reasons for so many deaths in the late December tsunami was because ... A: the tsunami is a wave with an extremely high wavelength and amplitude. A wave is the alternation ... | |
| inertia | 1/5/2005 |
| Q: what is inertia? what is permeability constant in magnetic properties? why is gravity independent of ... A: If you want to accelerate a mass then you have to apply a force to it. The mass exerts a force of ... | |
| Does Types of Surface Affect the Height and Amount of the Bounce of a Basketball? | 1/4/2005 |
| Q: Does Types of Surface Affect the Height and Amount of the Bounce of a Basketball? I research this ... A: my guess is that the type of surface has only a very minor impact on the height of the bounce. But ... | |
| different size | 1/4/2005 |
| Q: can the size of a trebuchet or throwing mechanism change the distance of an object being thrown? A: Of course the size of a trebuchet influences the distance an object can be hurled. A larger ... | |
| magnetism | 12/31/2004 |
| Q: I have heard that there are links between EMV and cancer but would a piece of magnet being worn as ... A: the first question is more a medicinical or biological question than a physical, but as far as I ... | |
| magnets | 12/28/2004 |
| Q: I purchased a christmas decoration that is held together by two small (tiny) magnets. The problem ... A: magnets have two poles at opposing sides, usually called north and south pole. North and south pole ... | |
| Black Holes/Viscosity | 12/28/2004 |
| Q: 2) I don't know exactly what calculation/formula you are referring to, but pressure, temperature and ... A: The density of course plays a role in the resistance of a body travelling through a gas, but ... | |
| electric field strength | 12/28/2004 |
| Q: I'd like to try one more follow-up, if I may. You say the electric field around the finite plane ... A: The field lines begin perpendicular to the plane in both cases (finite plate and section of the ... | |
| Black Holes/Viscosity | 12/28/2004 |
| Q: I have two questions: Question 1 - I have been learing about black holes, and I know that a black ... A: 1) Light has energy and because energy is equivalent to mass (E=mc^2) it also has mass. (Photons ... | |
| charge | 12/27/2004 |
| Q: Is there any difference between a charged object and electrically charged object? A: Electrical charge is just one of the charges that are affected respectively by the four fundamental ... | |
| relativity | 12/25/2004 |
| Q: Could you explain why (simply): It is assumed that nothing can reach the speed of light because as ... A: Energy and mass are equivalent (E=mc^2) and so adding kinetic energy (movement energy) to a mass by ... | |
| Time Dilation | 12/23/2004 |
| Q: What is physically happening in time dialtion? I know everything is relative and only happens in ... A: I wasn't clear enough about this: Time is not affected by speed. But time is not an absolute, ... | |
| Time Dilation | 12/23/2004 |
| Q: What is physically happening in time dialtion? I know everything is relative and only happens in ... A: What you have to understand is that time itself depends on the frame of reference you are moving ... | |
| atom | 12/20/2004 |
| Q: Let's say you have a smooth wood table and on top of it a rough stone. I assume the table, the ... A: ================= Thanks. Very interesting. However, I think you contradicted yourself. You said, ... | |
| atom | 12/18/2004 |
| Q: Let's say you have a smooth wood table and on top of it a rough stone. I assume the table, the ... A: To be non-transparent, the atoms or molecules must absorb the light. Most substances that are solid ... | |
| Orbit | 12/18/2004 |
| Q: Ok, odd question. Hypothetically, if you could chain the moon to the earth, with the following ... A: In first order approximation (presuming a massless, infinitely stong, inelastic chain strung between ... | |
| How best to illustrate a force carrier boson exchange? | 12/17/2004 |
| Q: I am doing research for a book and I am also a mechanical engineer, so feel free to get technical ... A: Your "frenzied mess of activity" picture is in my eyes quite a good layman's approximation of what ... | |
| gravitational forces | 12/16/2004 |
| Q: Do the Earth and Moon exert gravitational force on each other? Which one has the greatest ... A: Yes, like every mass exerts a gravitational force on every other mass, the earth and moon also ... | |
| Ullage pressure | 12/14/2004 |
| Q: What the term ullage pressure means? E.X. The tank's ullage pressure is 42 psi A: regarding your ratings of my answer: You gave me a rating of 8 out of 10 for timeliness. Since I ... | |
| optics | 12/13/2004 |
| Q: my name is vineeth venugopal and iam a student of class 12 in india. i have basic education in both ... A: If you would like to continue correspondence please feel free to ask me another question either by ... | |
| electric field strength | 12/12/2004 |
| Q: I am reading up on electric fields, and have been left with three puzzles in my mind, and would ... A: Sorry I didn't notice you posted a follow up question in your comment. (Better use the "follow up ... | |
Physics
Answers by Expert:
Kevin Johnson
Top Expert on this page
Expertise
I will try to answer any question in physics, but I do not provide homework solutions or project ideas. I have some teaching experience at university level but I am also skilled at explaining things in simple terms. My specialty areas are granular materials, computational physics, particle physics, quantum physics, econophysics and general physics. Questions in GERMAN are welcome, too.
Experience
I have graduated in physics, specialized in theoretical particle physics and quantum field theory, worked in the area of econophysics and am currently working on my PhD in granular materials and computational physics. I have some tutoring and teaching experience at University level.
Education/Credentials
German Diploma in Physics (equivalent to M.Sc)
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