BALLS: Happy and Unhappy
- Two balls of 25mm diameter apparently identical, do not behave the same when dropped or rolled because of their differing physical properties.
- The ‘happy’ ball bounces when dropped whereas the ‘unhappy’ ball hits the ground and stays there.
- When the balls are cooled below room temperature, the ‘happy’ ball bounce reduces and the ‘unhappy’ ball bounce increases.
- Instructions included.