Atomic Trampoline

This amazing toy gives us an insight into the behaviour of metals at an atomic level! There are two perspex tubes, and each has a circular lump of metal at the bottom. They appear pretty much identical. If you drop a ball bearing into the first tube, it falls onto the piece of stainless steel at the bottom, and it bounces a few times before stopping. The kinetic energy that it had originally has been dissipated. Some of it has been converted into sound - we hear the ball bearing hitting the metal. However