| MadSci Network: Physics |
Without a little more information it is hard to say what is going on with any certainty. What you are describing is somewhere between an elastic and inelastic collision. Inelastic collisions are hard to characterize well, so in Physics, people typically make assumptions about their system being perfectly elastic. So let's start there. Begin by thinking about how a ball bounces in the first place.
A falling ball hits the ground and at the point of impact, it has zero velocity - it stops. But, it deforms a little, and since the ball is springy, it stores some of the kinetic energy it had just before it hit the ground in the springiness of the ball. The ball has deformed and turned some of the kinetic energy into potential energy. After some (short!) time, the ball springs back and that potential energy is turned back into kinetic energy and the ball bounces up.
If you assume
that the practice balls have the same potential energy when they hit the
ground, perhaps the ball with fewer holes bounces higher because it has
less mass. Equal amounts of potential energy converted into kinetic energy
will make a ball with more mass bounce a shorter distance than a ball with
less mass. However, a ball falling with less mass would start out with
less kinetic energy than a ball with more mass - so it would have less to
convert into potential energy.
I hope this helps out some. Check out these web links:
Elastic
Collisions
Inelastic
Collisions
Simulator
for collisions
Another
simulator
Try the links in the MadSci Library for more information on Physics.