Re: Why does a ball bounce higher than another if it has higher air pressure?

Hello Erin,

As with most questions in physics, there are several correct answers.  The 
best that I can give you is that bouncing is most directly a product of 
molecular density.  If you have two rubber balls of identical material and size, 
but one is denser than the other (it has more molecules of matter packed into 
the same size), then the denser ball will bounce higher.  The molecules are 
pushed together when the ball strikes the floor and then they repel as they try 
to get back to their original position.  This movement of the molecules back to 
their places causes the bounce.  In a ball filled with air, there are more air 
molecules in the ball with higher air pressure.  While the molecules of the air 
do not behave precisely as those of a solid rubber ball, the principle is the 
same, when more molecules are present to be pushed together and then recoil 
against that push, the object will bounce higher.

(Note added by MadSci Admin:  we are implicitly not considering the overall 
effect of the total mass of the solid balls, but rather the density's effect on 
the "bounceability" of the ball.)

Thanks for the question!

Brian Self
Sherman High School Physics
Sherman, Texas