Posted by: george giles (george.giles@vanderbilt.edu) on Tue Jul 13 11:13:21 2010

Why steroid do not really help. The home run comes from the pitcher, not the batter if we consider momentum. The batter ideally reverses both the momentum vectior and the angular momentum.

Consider the bat as an elastic object anchored on one end (the hands). At the moment of impact the ball imparts energy into the elastic wooden bat. The hands anchor one end and at the instant of impact have no motion relative to the ball. The ball if it hits the antinode of the elastic bat (label) just falls to the ground or moves very slightly as the energy is dissipated as vibrations (batters hand hurts). Imagine the axis of rotational symmetry of the bat (center). If the ball impacts above center line you get a fly ball, below a grounder.

If and only if the batter hits the pitched ball on the center line of the ball, the axis of symmetry of the bat, and the node of the bat(sweet spot) does the batter achieve his desire; the home run.