Abstract:
Measurements are presented of the speed at which six different rods could be swung by four male students. Three of the rods
had the same mass but their swing-weight (i.e. moment of inertia) differed by large factors. The other three rods had the
same swing-weight but different masses. Our primary objective was to quantify the effects of mass and swing-weight on swing
speed. The result has a direct bearing on whether baseball, tennis, cricket and golf participants should choose a heavy or light
implement to impart maximum speed to a ball. When swinging with maximum effort, swing speed (V) was found to decrease
as swing-weight (Io) increased, according to the relation V = Cil.no, where C is a different constant for each participant and
n = 0.27 when 10 > 0.03 kg m2• Remarkably similar results were obtained previously with softball bats (where n = 0.25)
and golf clubs (where n = 0.26). Swing speed remained approximately constant as swing mass increased (when keeping
swing-weight fixed). The implications for racket power are discussed.
