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Physics/Science experiment HELP!! ASAP


QUESTION: Hello, Im doing a experiment for school and I also have to write a report for this.. My question is: Does the Mass of an object affect the speed in which it falls?' I am using different balls of different masses and dropping them.. I'm using Gallieo's experiemnt. But I have no idea whether to do them separately(as in drop them individually) or to drop and compare two at a time.. I also have to table up my results.. but I have no idea which method to use and how to table up the results.. I have a: tennis, pingpong, basketball, soccer and golf ball. and Im using a timer to record the time...

Which method should i do my experiment to answer my question? and how will I table up my results??

Thanks :)

ANSWER: This experiment has been done and, when properly done, will show that there's no effect on the speed with which an object falls due to its mass.  The problem is, you have a ping pong ball, which will suffer from drag.  

What you should do if you only have a hand timer is the following (as a starting point):  Roll the ball along a table where it will fall over the edge.  Horizontal and vertical velocity are unrelated, so the fact that it's going away from the table should in no way affect the vertical time.  Measure the fall times, repeatedly for each ball.  Take an average (roll each ball about 10 times) and make a table of the ball's mass (column 1) and its fall time (column 2).  Given constant acceleration, if they were affected differently by gravity they would show different fall times.  They won't, except for the really light balls, so just explain air drag going down in your report.  Further analysis is nice if you know the physics, but not necessary.

---------- FOLLOW-UP ----------

QUESTION: Ohhh.. thanks :) :) So, is this a good method to write int he scientific experimental report?

1.Prepare and set up all equipment, with the regards for all safety beforehand, creating a risk free environment.
2.Roll the balls to the edge of the bench to itís falling point and video the observations of the procedure.
3.Record the results in a data and time table by checking off which ball hit first the ground.
4.For this experiment, it is important to do multiple trails to make sure that the results are consistent. Repeat the experiment at least ten times for reliability.

Please help me decide weather it's good enough.. thanks :)

Aside from the common grammatical error ("it's" = "it is" while "its" is the possessive form), it's pretty good.  I'd say that step three should be a frame-by-frame analysis of the time it took each ball to fall to the ground instead of using the ambiguous statement about "checking off which ball hit first the ground."  That sentence also has a grammatical error, but you'll want to rephrase it to tell your instructor how you got the number (time) that you put in the table anyhow.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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