School of Physics Lecture Demonstration Manual

Mb-5 Happy and Unhappy Balls

Published: Thursday 09 March 2006 - Updated: Thursday 24 March 2011

Aim

To demonstrate the difference of coefficient of restitution of two balls that appear to be quite similar.

Apparatus

Happy and unhappy balls

Diagrams

Click on pictures to enlarge.

Happy and Unhappy Balls

Videos

Happy and Unhappy Balls

Description

By holding the two balls at the same height, and releasing them, one will bounce back to a similar height of release, while the other ball will hardly bounce at all. The happy ball, the one with greater bounce, has a high coefficient of restitution. The unhappy ball has a low coefficient of restitution, thus absorbing most of the energy of the fall.

Safety notes

Maintenance 

top of page