Number 150 (Story #4), November 5, 1993 by Phillip F. Schewe and Ben Stein THE PHYSICS OF BUNGEE JUMPING involves primarily the conversion of gravitational potential energy into the elastic energy of a stretched cord. Originating on Pentecost Island in the Pacific, the practice of a person jumping from a high place harnessed to a flexible attachment was introduced to Western culture in 1979 by the Oxford University Dangerous Sport Club. An all-important parameter, the amount by which the cord stretches at the bottom of the fall, should be accurately known in order to avert death. It is given by the following equation: extension = mg/K + squ root (m**2 g**2/ K**2 + 2mgl/K), where g is the gravitational acceleration, K is the cord's stiffness, L is the free length of the cord, and m is the mass of the plummeting object. (Paul Menz, Cumberland County College, in The Physics Teacher, Nov. 1993.)