This is a satisfyingly simple activity with surprising results. Take a tennis ball and place it on top of a basketball… then release both at the same time.
Instant ball launcher!
One of the basic laws of the universe is the conservation of momentum. When objects smack into each other, the momentum that both objects have after the collision, is equal to the amount of momentum the objects had before the crash. Once the two balls hit the ground, all the larger ball’s momentum transferred to the smaller ball (plus the smaller ball had its own momentum, too!) and thus the smaller ball goes zooming to the sky.
