Physics/Questions Answered by Expert David Montiel
| Subject | Date Asked |
| equilibrium | 10/5/2011 |
| Q: Why do high heels worn by a lady walking on a wooden floor leave impressions on the floor? Why do ... A: A pointy heel makes the pressure (weight/area) on the floor higher than that of a regular heel. The ... | |
| Physics | 10/3/2011 |
| Q: What force does a 2000kg truck experience if it comes to rest from a speed of 30m/s in 5s? I just ... A: You need to use F=ma. You would use W=mg if you had to calculate the weight of the truck (which you ... | |
| Waves | 9/30/2011 |
| Q: I'm a first year physics student in college and I've been finding my "Field, waves and light" ... A: The wavelengths that behave resonantly are the ones that fit an integer number of times in the twice ... | |
| Megnetic field and its effect on protons | 9/27/2011 |
| Q: Sir / Madam please tell me which pole of a magnetic field attracts or repels +ve charge. If +ve ... A: Magnets do not simply repel or attract electric charges in the way you seem to imply. They only ... | |
| Physics | 9/25/2011 |
| Q: Calculate the resultant velocity of an airplane that normally flies at 200 km/h if it encounters a ... A: No, you do not use that equation. You can only use c²=a²+b² if a and b are perpendicular. In this ... | |
| Torque as a vector | 8/17/2011 |
| Q: Many things dealt with in everyday use are vectors, and make sense as such. Velocity, for instance, ... A: I see why you are a little puzzled by this. That the direction of torque is along the axis of ... | |
| pseudo force | 8/15/2011 |
| Q: what is pseudo force? how and when do we apply pseudo force in a question? how do we identify a ... A: Pseudo force is a fictitious force (a force that is not really there) that APPEARS to be there in a ... | |
| Invention of the Wheel - Circular Shape | 8/10/2011 |
| Q: Invention of the Wheel ---------------------- There are Two Wheelers, Three Wheelers and Four ... A: I'm not an expert on this. There are several types of non-circular wheels used for very particular ... | |
| Human Being Resistance Power. | 7/31/2011 |
| Q: Human Being Body is a Good Conductor of Electricity (consists of watery fluids) since Water is good ... A: I do not think that there is anything special about people who have survived lightning strikes other ... | |
| Human Being Resistance Power. | 7/30/2011 |
| Q: Human Being Body is a Good Conductor of Electricity (consists of watery fluids) since Water is good ... A: Well it makes sense then that people with different "resistance power" could have a different ... | |
| Human Being Resistance Power. | 7/30/2011 |
| Q: Human Being Body is a Good Conductor of Electricity (consists of watery fluids) since Water is good ... A: 1.-The shock a person feels will be proportional to the current (I) passing through him/her. ... | |
| SPEED OF LIGHT | 7/19/2011 |
| Q: I have recently been re-reading a book called "Why does E =mc2 and why does it matter" which I have ... A: That is a very good question, and it makes a lot of sense. The trick here is that the argument ... | |
| electricity : resistance | 7/17/2011 |
| Q: Sir I have a doubt regarding the relation between POWER AND RESISTANCE . It is said , if a bulb ... A: About your first question, you are right, P=(V^2)/R so the more wattage, the lower the resistance. ... | |
| Apparent Weight in Water | 7/10/2011 |
| Q: A person who weights 740 N in air is lowered into a tank of water up to chin level. He sits in a ... A: The question is a bit tricky. Note that their asking for the NET force on the person when suspended ... | |
| acceleration | 7/9/2011 |
| Q: Sir.. i want to ask that what is an object doing if it is accelerating by 2 m/s... SIR.. give me ... A: I'm not sure what you're question is. If an object is accelerating it means it is increasing it's ... | |
| capillary action | 7/8/2011 |
| Q: I realize that a "capillary action engine" is impossible, but heres an interesting though experiment ... A: This is a good question. Occasionally, I come up with similar ideas for perpetual motion engines ... | |
| Beats | 7/7/2011 |
| Q: Two strings which are fixed at both ends are identical except that one is 0.65 cm longer than the ... A: First of all, the length of the string should be speed/[2*frequency]. So you should do 34.9/440 to ... | |
| expert analysis on sandia rocket sled test | 7/4/2011 |
| Q: well i ran into this sight, allexperts, digging around to answerer a question of speculations by ... A: OK I think I understand. I still find it hard to believe that a train engine can go up to 80mph in ... | |
| expert analysis on sandia rocket sled test | 7/4/2011 |
| Q: well i ran into this sight, allexperts, digging around to answerer a question of speculations by ... A: The video looks real to me. I agree with you that the rocket engines may have seemed unnecessary, ... | |
| Motion | 6/29/2011 |
| Q: Why is Displacement equal to the difference of final position and initial position? Can you please ... A: There is no proof, it is a definition. But maybe I can give you an example to help you understand it ... | |
| Time, Speed and Distance | 6/25/2010 |
| Q: Firstly, I am not requesting you to solve a text book problem. In fact, I could not really ... A: Sorry for the late reply. Your confusion is very common and totally understandable. The one thing ... | |
| physics | 6/20/2010 |
| Q: If you believe the atmoshere (firmament) keeps the waters above (humidity, clouds) from the waters ... A: I'll try to answer your question although I am not sure I fully understand it. Maybe you could help ... | |
| mixture temp | 5/2/2010 |
| Q: can u please tell me any formula 2 find the temperatre of mixture when 1) ice and water are mixed 2) ... A: Your question is a little long to explain. But it is a very common example. My advice is for you to ... | |
| auto collision | 4/5/2010 |
| Q: 2 cars each mass of 1000 kg and moving at speed of 20 m/s, collide and stick together. 1 car ... A: I'm really sorry for the delay, I was away and I forgot to set my status to "vacation"... It ... | |
| Light Speed + LHC | 4/1/2010 |
| Q: I have a question that you may be able to help with. I am struggling to understand light speed and ... A: Very good question and it is not at all strange. If I understand correctly, you are wondering ... | |
| relative velocity river boat problem. | 2/21/2010 |
| Q: I am having difficulty figuring out the width of the river. I am given: A river man can row his ... A: Hey Kat, My understanding is that the boat reaches the other end of the river 50 m downstream. But ... | |
| science | 2/19/2010 |
| Q: i have 8 paddle pop sticks, sticky tape, 2 meters of string, 5 serviettes and 2 pieces of A4 paper. ... A: Hey Sean, To be honest, I'm not very good at building things, and I remember failing at this very ... | |
| physics/speed | 2/14/2010 |
| Q: If you shoot a gun in a plane/jet going 1450 mph does the speed of the bullet, 1924 mph double? ... A: Yes, if you shoot a bullet inside a plane (and in the direction the plane is moving), the speed of ... | |
| Hot air | 2/6/2010 |
| Q: Why is hot air hot?? A: Well, I'm not sure I understand what you're asking, from the way you are phasing the question the ... | |
| physics-magnetism | 2/3/2010 |
| Q: respected sir, i will feel glad if you answer my simplewhy does magnetic north of a magnet attract ... A: sorry for the delay. Well, to describe the interaction (attraction or repulsion) between magnets, ... | |
| Classical Mechanics | 1/10/2010 |
| Q: We know that the equation for levers is F1D1=F2D2. First, does this only apply if the applied effort ... A: Yes, if you consider "D" to be the distance between the fulcrum and the point along the lever at ... | |
| magnification | 12/16/2009 |
| Q: how can a real image be magnified ? because a magnified image should have more no. of rays of light ... A: Interesting question, The answer is that you cannot really count the number of rays. For geometric ... | |
| Physics class egg drop | 12/15/2009 |
| Q: I have tried to think of some unique ways to do an egg drop but the stipulations are kinda tight. ... A: You know, I don't wanna get out of this one, but your guess is probably as good as mine. Go for the ... | |
| Addition of forces graphically. | 12/10/2009 |
| Q: i could do this problem, but i don't know how to find the measure of the angle. Paraphrase ofboy ... A: For the angle that the rope makes with the ground, the rope length is the hypotenuse and the height ... | |
| Light | 12/3/2009 |
| Q: Me and my friend were having a pretty competitive argument about the speed of light. I'm arguing ... A: If your friend is arguing that the speed of light (with respect to you) does not change regardless ... | |
| math | 12/1/2009 |
| Q: PLEASE READ THE FULL THING BEFORE REJECTING in school i am ahead in my math class so the teacher ... A: Don't worry I'm not rejecting your question. You seem to be a bit confused. Actually ANY number ... | |
| Ice | 11/30/2009 |
| Q: I realize that a skating blade generates a layer of water under pressure thus lubricating forward ... A: OK, I see. Well I couldn't tell you for sure but my guess is that below a certain temperature, the ... | |
| Universal Gravitation Constant | 11/26/2009 |
| Q: I have a question that i'm not sure how to start with. The question asks, "for the planet earth, ... A: Oops, looks like I put an extra "r"! (sorry) Your work seems to be correct except the speed is given ... | |
| Universal Gravitation Constant | 11/25/2009 |
| Q: I have a question that i'm not sure how to start with. The question asks, "for the planet earth, ... A: I don't think you have to use Kepler's Laws, since all those can be derived using the Law of ... | |
| comparison of human hearing ability vs. 24 bit (bluray) audio capabilities | 11/23/2009 |
| Q: The question I have is in regards to the ability of humans to hear vs. the audio information encoded ... A: Wow, looks like you already know quite a bit about this. On a personal level I find this stuff very ... | |
| Force and Gravity | 11/22/2009 |
| Q: 1.When an object is at rest, it has a weight. W=mg, When we push an object, the object is in motion ... A: I think I understand what you mean. The first thing that needs to be clarified is that the potential ... | |
| Force and Gravity | 11/21/2009 |
| Q: 1.When an object is at rest, it has a weight. W=mg, When we push an object, the object is in motion ... A: I think I understand your question now. As you mentioned yourself, while the earth orbits the sun, ... | |
| dielectric | 11/21/2009 |
| Q: F=-du/dx=-(1/2)*Q^2*d*[-(1-k)]/έ0*W*[x+k(l-x)]^2 how can i find frequency? i wounder if you ... A: Sorry for not getting back to you, I've been very busy lately. The truth is, finding the frequency ... | |
| Force and Gravity | 11/17/2009 |
| Q: 1.When an object is at rest, it has a weight. W=mg, When we push an object, the object is in motion ... A: Good questions. Although I find question 2 a bit confusing. First about question 1. I understand ... | |
| dielecric | 11/14/2009 |
| Q: i 'm really sorry for not paying attention carefully. any way i derivative from it but even now i ... A: God job! By the way, you DID find "F" as a function "x" ... | |
| capacitor | 11/11/2009 |
| Q: you ve asked me to answer what is the U(x). C1=έ0A/X for empty part ,and C2=έ0A/k(L-X ) ... A: There are three lenghts: One of them is d = the distance between the plates (thickness of the ... | |
| capacitor | 11/11/2009 |
| Q: you ve asked me to answer what is the U(x). C1=έ0A/X for empty part ,and C2=έ0A/k(L-X ) ... A: You're on the right track! And yes, you can suppose that these 2 parts are like 2 parallel ... | |
| capacitor | 11/9/2009 |
| Q: you mean that i must use U=1/2(kx2) and differentiate from it so its result is F=-kx but we knew ... A: No, obviously you can't use U=1/2(kx2), cause that would be assuming beforehand that the capacitor ... | |
| capacitor | 11/8/2009 |
| Q: i am really sorry for typing badly and i hope i could tell my question better than before. if we put ... A: You have to find dU/dx NOT ΔU/Δx because they are not equal unless the force is constant ... | |
| capacitor | 11/8/2009 |
| Q: i am really sorry for typing badly and i hope i could tell my question better than before. if we put ... A: OK Sanaz, I think I understand your question now. In the problem they don't ask you for the ... | |
| capacitor | 11/7/2009 |
| Q: i am really sorry for typing badly and i hope i could tell my question better than before. if we put ... A: I'm still confused about the question. Please let me know: Do you put the dielectric, and then ... | |
| physics | 11/5/2009 |
| Q: can the resultant of two vectors of the same magnitude be equal to the magnitude of either of the ... A: The answer to your question is yes, it can. The figure I attach shows an example of this. Vectors A ... | |
| How does sound travel | 11/3/2009 |
| Q: My question is how does sound travel through the air? Is it like a radio wave? And is sound inside a ... A: Yes, you always use I0=1*10^-12 W/m^2 in the formula. ...although of course this number does not ... | |
| How does sound travel | 11/2/2009 |
| Q: My question is how does sound travel through the air? Is it like a radio wave? And is sound inside a ... A: Decibels (dB) are a measure of sound intensity, but on a logarithmic scale. The formula is: dB = ... | |
| Quantum Mechanics | 11/2/2009 |
| Q: Consider a particle in a 1-D box with impenetrable walls at x=0 and x=L. Then the eigen function for ... A: Good question! I can tell you have put some thought into it. Your solution and reasoning are ... | |
| multiverse | 11/1/2009 |
| Q: I finsihed reading Brian Green's book where he discusses a Multiverse (many universes) and it ... A: I don't really know anything about Multiverses and I forgot what Brian Green's book says about ... | |
| How does sound travel | 10/26/2009 |
| Q: My question is how does sound travel through the air? Is it like a radio wave? And is sound inside a ... A: No, sound waves and radio waves have a different nature. Radio waves belong to a type of waves ... | |
| physics(electrostatics) | 10/24/2009 |
| Q: am stuck on a question, hav gotten one part but cant seem to know were am to go from here. d ques ... A: The best way to answer your question would be using a diagram. Unfortunately I don't have the means ... | |
| General Physics | 10/20/2009 |
| Q: I am a high school junior, and I am taking a high school regents level physics course this year. I ... A: A sphere is a mathematical model to which we usually "fit" to many shapes that occur in nature (like ... | |
| Potential U(x) | 10/17/2009 |
| Q: Why we can express the potential U(x) in a Taylor series about a certain equilibrium point? Ex. ... A: You can express any continuous and differentiable function about any point using a Taylor series ... | |
| Physic Laws | 9/26/2009 |
| Q: I have a very simple question. What is the criteria to be classified as a law? Why is the law of ... A: A law is a statement that expresses a fundamental principle of science. To qualify as a law, this ... | |
| action/reaction | 9/25/2009 |
| Q: 1. In a generic case of a mass point and an extended body to interact with gravitational force, the ... A: Being rigorous, every point of the extended body interacts with the point mass. You can model this ... | |
| Why do orbits decay? | 9/17/2009 |
| Q: My brother and I were talking about the Hubble Telescope. During that conversation we both wondered ... A: You are right, in order for an orbit to decay, the object must lose kinetic energy. Normally this ... | |
| Vectors | 9/16/2009 |
| Q: How can I find the range of a cannon if I know its initial velocity assuming that it is set to an ... A: If the height of the cannon is the same as the height of the point where the ball lands (the cannon ... | |
| about are lesson i repport it tommorow | 9/10/2009 |
| Q: what is the meaning of contact and field force? pleas give some example! A: I believe "contact force" is the electrosatic repulsion force that arises when two objects are in ... | |
| what is this physics law called and how does it work | 9/9/2009 |
| Q: if i can remember back years ago...there is a law that if there is an object (let's say a wall) and ... A: Well, the opposite is definitely true. There is a force that makes objects attract each other, it's ... | |
| what is this physics law called and how does it work | 9/9/2009 |
| Q: if i can remember back years ago...there is a law that if there is an object (let's say a wall) and ... A: As far as I know, aside from air resistance (which, in principle, would have nothing to do with the ... | |
| physics | 9/8/2009 |
| Q: Could you help me give a mathematical explanation on the Conservation of Angular Momentum? A: The conservation of angular momentum is a consequence of Newton's Second Law, which can be written ... | |
| quantum | 9/7/2009 |
| Q: I'm reading a book by Paul Davies and I just want to clear something in my own mind. I understand ... A: I am not quantum mechanics expert but all I know is, yes, it looks like under a particular ... | |
| The Math of Physics | 9/2/2009 |
| Q: I am self teaching. Unfortunately I have issues which make it impossible for me to attend school at ... A: Wow, I admire your enthusiasm and determination! Good for you! OK, first of all my advice is that ... | |
| dielectric | 9/1/2009 |
| Q: why the presence of dielectric decreases the coulomb`s force? charges are also present in dielectric ... A: Sorry Seep, it looks like I misread your question and actually gave you a wrong answer. A ... | |
| dielectric | 8/29/2009 |
| Q: why the presence of dielectric decreases the coulomb`s force? charges are also present in dielectric ... A: The presence of a dielectric DOES NOT decrease the Coulomb force (if by this you mean the force ... | |
| another question | 8/27/2009 |
| Q: .why magnetism arise in a conductor carrying current? what is the phenomenon involved in it? ... A: OK, I think I understand better now. Thanks for clarifying. For question 1, Brownian motion is the ... | |
| PHYSICS maxwell's electromagnetics | 8/27/2009 |
| Q: in Maxwell's equation of Faraday's law : "curl(E)= -dB/dt" . It is well known that the right side of ... A: Update: John, I've done a little revision of Faraday's Law of induction and I hope I can give you ... | |
| magnetism | 8/26/2009 |
| Q: .why magnetism arise in a conductor carrying current? what is the phenomenon involved in it? A: Magnetic fields (magnetism) are created by moving charges. There is no explanation beyond that: ... | |
| PHYSICS maxwell's electromagnetics | 8/25/2009 |
| Q: in Maxwell's equation of Faraday's law : "curl(E)= -dB/dt" . It is well known that the right side of ... A: As far as I know the implication works both ways. If you measure a curl in E, there must be ... | |
| Time | 8/23/2009 |
| Q: Does time have a defined speed, not relative to any interaction? A: I'm not sure if you are aware of it but that is an very profound question, in the sense that there ... | |
| Please help me with solving this physics question. | 8/21/2009 |
| Q: Calculate the time it takes a plane travelling at a constant tangential speed of 110m/s to fly once ... A: Before I get to your question, I should let you know that my policy is not to give full solutions to ... | |
| Energy Comparison | 8/20/2009 |
| Q: Can you tell me how I would find the answer to establishing how many ltrs of compressed air at say ... A: I would advise you to ask someone in the Thermodynamics field on Chemical Engineering. An expert ... | |
| Energy Comparison | 8/19/2009 |
| Q: Can you tell me how I would find the answer to establishing how many ltrs of compressed air at say ... A: Vince, I'm sorry but your question still doesn't make a lot of sense to me. First of all, I'm not ... | |
| Energy Comparison | 8/19/2009 |
| Q: Can you tell me how I would find the answer to establishing how many ltrs of compressed air at say ... A: I'm not sure I understand your question. When you say "equal", what do you mean exactly? Equal in ... | |
| Thermal Physics | 8/18/2009 |
| Q: I have spent time trying to understand and answer the following question. Would you be so kind to ... A: Before I get to your question, I should let you know that my policy is not to give full solutions to ... | |
| forces and friction question. | 8/16/2009 |
| Q: Montiel, I hope you are well. My name is Ken and live in Calgary.I have an assignment question that ... A: Everything you wrote down looks correct to me. I tried to solve the problem on my own and I think ... | |
| roulette | 8/14/2009 |
| Q: Hy, I have a question regarding the roulette. How can we calculate the ball circulation? Which ... A: This is a very interesting question. You could say that the ball on the roulette is subject to many ... | |
| physics | 8/13/2009 |
| Q: I'm rusty at this. The formula for free fall motion I'm told is d = 1/2at2 (can't find the ... A: First, let me give you a tip for future reference. There is no superscript for "squared" on the ... | |
| charges | 8/12/2009 |
| Q: i wanted to ask that why in a capacitor the charges are not neutralised when there is no dielectric ... A: I'm going to assume that by "neutralised" you mean that there is no longer a net charge in any of ... | |
Physics
Answers by Expert:
David Montiel
Top Expert on this page
Expertise
PLEASE READ THIS BEFORE POSTING YOUR QUESTION: While I am glad to offer HELP with problems, I refuse to SOLVE problems. There is a difference. Please do not just copy a question from a texbook or assignment. I WILL REJECT IT. I will only accept questions if, in addition to the statement of the problem, you describe in detail what you have tried so far in order to solve it, and what exactly is the problem you are encountering. In other words where/why are you stuck? I can answer general physics questions up to the level of first or second year undergraduate courses. Topics I am familiar with include: classical mechanics (kinematics, dynamics, etc.), electricity and magnetism, optics, thermodynamics, and special relativity. I may not answer questions at an advanced undergraduate or graduate levels. Also please do not expect help with algebra or arithmetic (performing numerical calculations).
Experience
I have been a private physics tutor for about eight years. I also have six years of experience a teaching assistant (for both theory and lab) and occasional substitute lecturer in Physics.
Education/Credentials
B.S. in Chemical Engineering
M.S. in Chemical Physics
PhD in Physics.
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