These colliding steel spheres will help demonstrate the Law of Conservation of Energy, and show students how mechanical systems convert energy to heat. When objects collide, the kinetic energy transforms into sound, heat, and kinetic energy in the opposing direction. These steel spheres are a fantastic way to show kids how energy “loss” is actually energy being released as heat! When these two (2) 0.5lb steel spheres are smashed together, the kinetic energy transforms into enough heat to burn a hole through a piece of paper! Balls are 1.5" in diameter and sold as a pair. Comes with a Teacher's Guide.