Experiments with colliding rods

Abstract

When a short rod collides end-on with a long rod, kinetic energy is not conserved since the longer rod vibrates after the collision. In theory, the fractional energy loss is equal to 1 − L 1/L 2 where L 1 is the length of the short rod, L 2 is the length of the long rod, and the long rod is initially at rest. Measurements of the energy loss are presented for a set of steel rods and a set of wood dowels. The steel rods were shorter than the dowels and behaved more like steel balls, with only a small decrease in kinetic energy. A larger fractional energy loss was observed when using the dowels since a larger fraction of the initial kinetic energy was converted to vibrational energy in the dowels. In neither case was the energy loss equal to 1 − L 1/L 2.