**PIRA Code(s):** 1D15.45

**Set up time:**1 minute

**Operation:** Place balls of equal mass and size at the top of the tracks, one at the cycloid, one at the parabola, and one at the straight track. Let the balls roll down, the cycloid ball will arrive first. Then, place two balls on the cycloid track, one at the top and one a little ways down. The two balls will reach the end at the same time.

**Physics and Science Concepts:** Motion in Two Dimensions

**Safety:** None