Listening to the coefficient of restitution-revisited

We present a new method for measuring the coefficient of restitution betwee n a steel ball and a hat, smooth surface, based on the recording of sound f iles with a PC. We demonstrate how a simple and straightforward analysis of the sound files yields the coefficient of restitution as a function of vel ocity. The time resolution of many PC sound cards allows us to measure the collision time and hence to estimate the average impulsive force and the st ress exerted on the surface. This in turn provides a basis for a discussion of energy loss mechanisms. (C) 2001 American Association of Physics Teache rs. Teachers.