Consists of a series of five steel balls attached to the bottom of v-shaped lengths of string, which is supported by a frame.

There are two available in the demo room. One looks more like the classic Newton's cradle, with string and a steel frame. The other uses pieces of injection-molded plastic in place of the string and a bigger plastic frame, but actually functions better since the balls are lined up better and the plastic doesn't dissipate as much energy as the string.

A classic demonstration. Demonstrate elastic collisions, conservation of momentum, conservation of energy, and pendulums. Show how non-perfectly-elastic collisions dissipate energy.

• Newton's Cradle

Lift a ball on one side and release it. It'll swing down and hit the rest of the balls, causing the ball on the opposite side to be shoved out. You can also lift multiple balls- lift any number, and that number of balls will bounce out the other side. Lift three, and the center ball will always be in motion.

Despite appearances the plastic one works substantially better. Use it unless you're concerned about appearance.