The sweet spot of a baseball bat

The sweet spot of a baseball bat, like that of a tennis racket, can be defined either in terms of a vibration node or a centre of percussion. In order to determine how each of the sweet spats influences the "feel" of the bat, measurements were made of the impact forces transmitted to the hands. Measurements of the bat velocity, and results for a freely suspended bat, were also obtained in order to assist in the interpretation of the force waveforms. The results show that both sweet spots contribute to the formation of a sweet spot zone where the impact forces on the hands are minimised. The free bat results are also of interest since they provided particularly elegant examples of wave excitation and propagation, suitable for a student demonstration or experiment. (C) 1998 American Association of Physics Teachers.