Some balls bounce better than others.
A particular ball can be characterized by its
coefficient of restitution:
The ratio of its rebound speed Vf to its collision speed
when its bounces off a hard, stationary surface that can't move.
coefficient of restitution r = Vf /
Scientists have found that, for most balls, this speed ratio
remains constant over a wide range of collision speeds.
The amount of kinetic energy transformed at impact is called
the collision energy (become thermal energy).
This java applet shows you the effects due to
different coefficient of restitution.
1. You can enter different value of coefficient of restitution as
Then, press return key to start the animation.
2. You can change the initial velocity Vx of the ball.
Click near the tip of bluearrow
( represent its velocity)
3. You can change the initial height (drag it up and down with mouse
4. Press Start button to start/restart animation.
The animation will stop automatically when it bounces off the screen.
4. Press Reset button to reset parameters to its default value.
It also clear the screen.
5. Press the mouse button to pause the animation
If you click the left mouse button,
6. The mouse coordinate (X,Y) will be shown when its inside the window.
animation will resume when you release it.
If you click the right mouse button,
you need to click it again to resume.
You will know the timing t from (X and velocity Vx)
You should be able to get some graph like this (click
Your suggestions are highly appreciated!
E-mail : Please click firstname.lastname@example.org
Author¡GFu-Kwun Hwang, Dept. of physics, National Taiwan Normal University
Last modified :
Subject: bouncing ball
Date: Fri, 21 Apr 2000 05:01:29 -0400
From: David and Carol <email@example.com>
the above site has been helpful in a differential equations project I am
currently undertaking. One thing that would make your applet invaluable to
me is if heights were marked on the picture of the bouncing ball. I am
measuring the height of a ball and am trying to find it's coefficient of
restitution. Is there anyway of setting initial heights on your applet and
finding the maximums of each consecutive bounce?
The code was modified according to David's suggestion Apr. 21, 2000