The Physics of Stone Throwing

Prompted by his son's questions on the subject and the need to furnish his mechanics textbook with commonplace examples, physicist Lyderic Bocquet of the Universite Claude Bernard Lyon (France) has investigated the science behind stone skipping. The chief parameters that determine whether your stone goes right in or skims across the lake are as follows: the mass of the stone, its angle with respect to the horizon, its angle with respect to the water surface (lower is better), its spin rate (more is generally better, for stability), and its horizontal velocity. Armed with calculations on energy loss, Bocquet (33-472-43-2796) has worked out an expression for the maximum number of skips one can expect. According to Bocquet, the world's record for stone rebounds is 38. (American Journal of Physics, February 2003; see also http://lpmcn.univ-lyon1.fr/~lbocquet )