Drop the stack of balls straight down on a hard surface (the floor is best), and the top ball will bounce up to five times the height of the original drop.

Elastic collisions:

Conservation of kinetic energy and linear momentum can be seen from analyzing the collisions among the individual balls. For example, consider the collision between the blue and green balls. Think of the blue ball hitting the ground first and then bouncing upward with the same speed. The less massive green ball is still moving downward when the blue ball starts upward, so they collide.

Demonstrates:

• Elastic collisions
• Supernova shock waves