Super bounce

HOW

1. Lift the balls together to a height of about 1 metre and drop them freely.
2. Observe how high each one bounces.

WHY

During the bounce of the balls falling together, the total mechanical energy and total momentum of the balls are conserved. The bounce phenomenon takes place in successive stages over a very short time interval. These include:

• bounce of the lower, heaviest ball off the ground,

• its collision (with upward movement) with the still falling medium ball,

• collision of the medium ball already moving
upwards with the still falling upper, lightest ball.

In such a collision, the top ball with the least mass will gain additional energy at the expense of the other, larger ones. As a result, it will rise to a greater height than that from which it fell.