Motion Commotion

Open this magazine in the middle and roll a marble down the center onto a plate. The marble shot right off the plate, didn’t it?

Now place a second marble on the plate, just at the bottom of the center of the magazine, and roll the first marble down it again. What happened to both marbles?

There are two scientific principles at work here:

1. Nothing moves unless a force of some kind moves it.

2. Whenever something moves in one direction, an equal force moves in the opposite direction.

Thus, gravity was the force that moved the first marble, and the force of the first marble moved the second marble. When the first marble hit the second marble, the impact made the first marble react against its own force in the opposite direction, thus making the marble stop.