The bouncing of happy balls and other objects

Physics of the Mundane

Adam Johnston

We have seen objects falling down as rising skyward.  Now we wish to analyze a transition from one direction of motion to the other.  You probably already have an idea of how different things bounce, but today we want to investigate bouncing properties more completely.

You should have an assortment of balls, definitely including:

! a happy ball (a.k.a. super ball or rubber ball)

! a ping pong ball

! a steel ball (various sizes)

! a clay ball

and possibly including some of the following:

! a golf ball

! a large super ball

! a racket ball

! a hand ball

! a tennis ball

! others?

You should also have a meter stick or some other length measuring device.  With these materials, show the relationship between the initial Arelease height@ (height from which you drop the ball) and Abounce height@ (height that the ball bounces back up to).  You should graph release height on the horizontal axis of a graph (since it is your independent variable) and bounce height on the vertical axis of a graph (since it is your dependent variable).  Describe the relationship between these two heights.  Is there a maximum bounce height for a given object, regardless of release height?  (Perhaps we should seek giant release heights?)

Most importantly: Explain why some balls bounce higher than others.  What characteristic allows for the greatest bounce?  What would be required for a ball to bounce back up to its original height, assuming that you simply dropped it?

Something to think about: Why doesn=t a ball ever bounce higher than the height from which it is released?