1n30.22: HAPPY AND UNHAPPY BALLS

DEMONSTRATES: Coefficients of restitution.

EQUIPMENT: Happy and unhappy balls.

DESCRIPTION: Drop the two balls simultaneously from the same height. One bounces back to almost the original height, while the other stops dead on impact. Which one will be able to knock over a board and which will not?

COMMENTS: A very large version which consists of two basketballs is available for large lecture halls.

KEYWORDS: happy and sad balls, coefficient of restitution