Function for the velocity of a bouncing ball

AI Thread Summary
The discussion centers on the mathematical relationship between the height from which a bouncing ball is dropped and the time it takes to bounce multiple times. A quadratic function is observed, attributed to the constant acceleration of the ball during free fall, where displacement is proportional to the square of time. The coefficient of restitution (b) affects the height achieved after each bounce, with energy loss leading to a reduced height proportional to b. Clarifications are sought regarding the interpretation of energy and height, particularly how the coefficient of restitution influences the ball's behavior. The conversation concludes with an agreement on the mathematical principles involved.
Jeven
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I graphed different heights from which I had dropped a bouncing rubber ball on the y-axis and the time taken for it to bounce on the x-axis. The function came out to be quadratic, but I do not know why. If someone can show mathematically why this is, that'd be splendid. Thank you.
 
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Jeven said:
I graphed different heights from which I had dropped a bouncing rubber ball on the y-axis and the time taken for it to bounce on the x-axis. The function came out to be quadratic, but I do not know why. If someone can show mathematically why this is, that'd be splendid. Thank you.
What do you exactly mean by the time taken for it to bounce? Is it the time taken for it to reach to the ground or to reach the ground and bounce a few times and stop due to loss of energy?
 
Jeven said:
I graphed different heights from which I had dropped a bouncing rubber ball on the y-axis and the time taken for it to bounce on the x-axis. The function came out to be quadratic, but I do not know why. If someone can show mathematically why this is, that'd be splendid. Thank you.
It is motion with constant acceleration. How is the displacement related to time?
 
Guneykan Ozgul said:
What do you exactly mean by the time taken for it to bounce? Is it the time taken for it to reach to the ground or to reach the ground and bounce a few times and stop due to loss of energy?
I am sorry I forgot to add that the time is the time taken for it to bounce 5 times.
 
Jeven said:
I am sorry I forgot to add that the time is the time taken for it to bounce 5 times.
Okay. Now, let's say that acceleration is constant a . Now the velocity at time t will be at. Then the displacement d=∫atdt=1/2at^2 assuming that the initial position is 0.
Now let's say that the ball hits the ground and the energy of the ball reduces to bE where E is the energy of the ball before it hits the ground and b is a some arbitrary constant. Now the particle will go to 1/b of initial height then the time will be √(1/b) of the time it takes to hit the ground. So if you do this 5 times you will find the total time. If b is 1, that is ball does not lose energy when it hits the ground you will get directly get only quadratic term since d is proportional to square of t. If b is bigger than 1, still the leading term will be square of t. So it is a quadratic.
Hope this is helpful.
 
Guneykan Ozgul said:
Okay. Now, let's say that acceleration is constant a . Now the velocity at time t will be at. Then the displacement d=∫atdt=1/2at^2 assuming that the initial position is 0.
Now let's say that the ball hits the ground and the energy of the ball reduces to bE where E is the energy of the ball before it hits the ground and b is a some arbitrary constant. Now the particle will go to 1/b of initial height then the time will be √(1/b) of the time it takes to hit the ground. So if you do this 5 times you will find the total time. If b is 1, that is ball does not lose energy when it hits the ground you will get directly get only quadratic term since d is proportional to square of t. If b is bigger than 1, still the leading term will be square of t. So it is a quadratic.
Hope this is helpful.
Yes it is thank you. But I don't quite understand the (1/b) part, why would that be the energy? And what would I do to make this function a linear function? Because I need to graph a straight line.
 
Guneykan Ozgul said:
Okay. Now, let's say that acceleration is constant a . Now the velocity at time t will be at. Then the displacement d=∫atdt=1/2at^2 assuming that the initial position is 0.
Now let's say that the ball hits the ground and the energy of the ball reduces to bE where E is the energy of the ball before it hits the ground and b is a some arbitrary constant. Now the particle will go to 1/b of initial height then the time will be √(1/b) of the time it takes to hit the ground. So if you do this 5 times you will find the total time. If b is 1, that is ball does not lose energy when it hits the ground you will get directly get only quadratic term since d is proportional to square of t. If b is bigger than 1, still the leading term will be square of t. So it is a quadratic.
Hope this is helpful.

if b is the coefficient of restitution, COR, which is less than 1,then why would it go to 1/b of the initial height, meaning it would surpass the initial height since 1/COR>1 ?? I see you know your stuff so I must be at a loss here so could you please explain your meaning :)
 
Belovedcritic said:
if b is the coefficient of restitution, COR, which is less than 1,then why would it go to 1/b of the initial height, meaning it would surpass the initial height since 1/COR>1 ?? I see you know your stuff so I must be at a loss here so could you please explain your meaning :)

He just made some little confusion I guess.
If the energy of the ball at the initial peak h_0 is E_0 = mgh_0, after the bounce you'll have, again at the peak, E_1 = bE_0 = mgbh_0, so h_1=bh_0.
 
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