Crash one ball in a group of four balls and only one ball shoots out. Smash it faster into the group of balls and still only one ball shoots out. Why don't two or three? Students learn the fundamentals of the laws of conservation of energy and momentum with this hands-on collisions lab. An excellent introductory kit that can also be used by advanced classes. Kit includes five steel ball bearings of the same size and mass, a 75-cm long metal track, and complete laboratory instructions. Larger ball bearings can be used for further investigation. Classroom set includes enough tracks and balls for eight student groups.