youngvuth Posted April 30, 2017 Share Posted April 30, 2017 I am supposed to find out how mass affects the time it takes a ping pong ball to fall a certain distance. Can somebody help with information please? My belief is that the more water the faster it'll fall. Link to comment Share on other sites More sharing options...
Roger Dynamic Motion Posted April 30, 2017 Share Posted April 30, 2017 My belief is that the more water the faster it'll fall. ___ / What does that mean ? -1 Link to comment Share on other sites More sharing options...
StringJunky Posted April 30, 2017 Share Posted April 30, 2017 I am supposed to find out how mass affects the time it takes a ping pong ball to fall a certain distance. Can somebody help with information please? My belief is that the more water the faster it'll fall. If you drop a feather and a cannon ball, at the same time in a volume with no air in it, they will touch the bottom at the same time. What does that tell you about the effect of mass on the rate an object falls? Link to comment Share on other sites More sharing options...
Roger Dynamic Motion Posted April 30, 2017 Share Posted April 30, 2017 (edited) The mass will created a force at the contact time with the surface much greater than the feather Edited April 30, 2017 by Roger Dynamic Motion Link to comment Share on other sites More sharing options...
StringJunky Posted April 30, 2017 Share Posted April 30, 2017 (edited) The mass will created a force at the contact time with the surface much greater than the feather But that doesn't mean it's falling faster This is done in a very large vacuum chamber: Edited April 30, 2017 by StringJunky 2 Link to comment Share on other sites More sharing options...
Roger Dynamic Motion Posted April 30, 2017 Share Posted April 30, 2017 (edited) This is done in a very large vacuum chamber: No ~ the time of the fall is relative... Edited April 30, 2017 by Roger Dynamic Motion -4 Link to comment Share on other sites More sharing options...
Strange Posted May 1, 2017 Share Posted May 1, 2017 This is done in a very large vacuum chamber: No ~ the time of the fall is relative... Relative to what? I am supposed to find out how mass affects the time it takes a ping pong ball to fall a certain distance. Can somebody help with information please? My belief is that the more water the faster it'll fall. Are you considering air resistance? In which case, the mass will make a difference because the terminal velocity will be higher: https://en.wikipedia.org/wiki/Terminal_velocity Link to comment Share on other sites More sharing options...
pzkpfw Posted May 1, 2017 Share Posted May 1, 2017 ( ...and on the Moon: ) 2 Link to comment Share on other sites More sharing options...
StringJunky Posted May 1, 2017 Share Posted May 1, 2017 ( ...and on the Moon: ) Forgot about that one. Link to comment Share on other sites More sharing options...
Strange Posted May 1, 2017 Share Posted May 1, 2017 ( ...and on the Moon: ) That might be beyond the budget of a school science experiment, though... 1 Link to comment Share on other sites More sharing options...
MigL Posted May 1, 2017 Share Posted May 1, 2017 Not sure I quite understand the experiment, but he may be adding mass to the ping-pong ball by filling it with water. If he then drops it and measures the time to fall, he will have a variable mass but constant air resistance. Link to comment Share on other sites More sharing options...
StringJunky Posted May 1, 2017 Share Posted May 1, 2017 Not sure I quite understand the experiment, but he may be adding mass to the ping-pong ball by filling it with water. If he then drops it and measures the time to fall, he will have a variable mass but constant air resistance. He'll record the same times, won't he? Link to comment Share on other sites More sharing options...
pzkpfw Posted May 1, 2017 Share Posted May 1, 2017 (edited) He'll record the same times, won't he? Not when dropped in air. Air causes drag. Drag is a force. The different masses of the pin pong ball and ping pong ball full of water then makes a difference. ( Extreme example: a parachutist vs a parachutist whose chute didn't open - same mass, different rate of fall. Of course, the two ping pong balls have the same shape, but ... ) https://www.quora.com/If-we-drop-different-weights-from-same-height-which-will-fall-first-to-ground Edited May 1, 2017 by pzkpfw Link to comment Share on other sites More sharing options...
Roger Dynamic Motion Posted May 1, 2017 Share Posted May 1, 2017 (edited) The question was !~ If you drop a feather and a cannon ball, at the same time in a volume with no air in it, they will touch the bottom at the same time. What does that tell you about the effect of mass on the rate an object falls? No ~ the time of the fall is relative... to any object falling in vacuum. Edited May 1, 2017 by Roger Dynamic Motion -1 Link to comment Share on other sites More sharing options...
StringJunky Posted May 1, 2017 Share Posted May 1, 2017 (edited) Not when dropped in air. Air causes drag. Drag is a force. The different masses of the pin pong ball and ping pong ball full of water then makes a difference. ( Extreme example: a parachutist vs a parachutist whose chute didn't open - same mass, different rate of fall. Of course, the two ping pong balls have the same shape, but ... ) https://www.quora.com/If-we-drop-different-weights-from-same-height-which-will-fall-first-to-ground I thought if all parameters stay the same, except the mass, it would be the same effect as if they were in a vacuum; the degree of drag would be the same because they are the same size and shape and force of gravity would be the same. The only difference in results between the experiment done in a vacuum and air is the actual time it takes for the objects to fall in either setup. Edited May 1, 2017 by StringJunky Link to comment Share on other sites More sharing options...
pzkpfw Posted May 1, 2017 Share Posted May 1, 2017 I thought if all parameters stay the same, except the mass, it would be the same effect as if they were in a vacuum; the degree of drag would be the same because they are the same size and shape and force of gravity would be the same. The only difference in results between the experiment done in a vacuum and air is the actual time it takes for the objects to fall in either setup. Mass is one of the factors in terminal velocity. So the weighted ball will get faster than the unweighted ball. (Been trying to find a good worked example. For a start: https://en.wikipedia.org/wiki/Terminal_velocity#Derivation_for_terminal_velocity ) Link to comment Share on other sites More sharing options...
StringJunky Posted May 1, 2017 Share Posted May 1, 2017 Mass is one of the factors in terminal velocity. So the weighted ball will get faster than the unweighted ball. (Been trying to find a good worked example. For a start: https://en.wikipedia.org/wiki/Terminal_velocity#Derivation_for_terminal_velocity ) So, what you are saying is that there is reaction between the mass and air that is not present in a vacuum? Link to comment Share on other sites More sharing options...
MigL Posted May 1, 2017 Share Posted May 1, 2017 (edited) In a vacuum there is no terminal velocity. The acceleration of any test mass is solely dependent on the mass of the Earth ( little m cancels out from ma=GmM/r^2) and radius. While in air, when the gravitational force is equal to the drag force, there is no more acceleration. And since drag is NOT dependent on mass, m cannot cancel out. I.E. we have a mass ( m ) dependence to acceleration and terminal velocity. Edited May 1, 2017 by MigL 2 Link to comment Share on other sites More sharing options...
StringJunky Posted May 1, 2017 Share Posted May 1, 2017 In a vacuum there is no terminal velocity. The acceleration of any test mass is solely dependent on the mass of the Earth ( little m cancels out from ma=GmM/r^2) and radius. While in air, when the gravitational force is equal to the drag force, there is no more acceleration. And since drag is NOT dependent on mass, m cannot cancel out. I.E. we have a mass ( m ) dependence to acceleration and terminal velocity. OK. Thanks. Link to comment Share on other sites More sharing options...
Strange Posted May 1, 2017 Share Posted May 1, 2017 The question was !~ If you drop a feather and a cannon ball, at the same time in a volume with no air in it, they will touch the bottom at the same time. What does that tell you about the effect of mass on the rate an object falls? No ~ the time of the fall is relative... to any object falling in vacuum. I have no idea what that is supposed to mean. But it sounds wrong. In a vacuum the feather and the canonball will fall at the same rate and hit the floor at the same time. The time is not relative to the mass (or shape) of the objects. Link to comment Share on other sites More sharing options...
Roger Dynamic Motion Posted May 1, 2017 Share Posted May 1, 2017 (edited) The time of the fall is relative..''with any environment'', to any object falling trough vacuum or trough the air Edited May 1, 2017 by Roger Dynamic Motion -1 Link to comment Share on other sites More sharing options...
Strange Posted May 1, 2017 Share Posted May 1, 2017 The time of the fall is relative..''with any environment'', to any object falling trough vacuum or trough the air What does that even mean? Link to comment Share on other sites More sharing options...
Roger Dynamic Motion Posted May 2, 2017 Share Posted May 2, 2017 (edited) the one is the same to the other.. only different with the result @!~ Edited May 2, 2017 by Roger Dynamic Motion Link to comment Share on other sites More sharing options...
Manticore Posted May 2, 2017 Share Posted May 2, 2017 the one is the same to the other.. only different with the result @!~ Guaranteed content free. 1 Link to comment Share on other sites More sharing options...
Strange Posted May 2, 2017 Share Posted May 2, 2017 the one is the same to the other.. only different with the result @!~ This makes no sense. Link to comment Share on other sites More sharing options...
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