SPIN, TRAJECTORY, AND MOTION - IN THE CASE OF BASEBALL AND SOFTBALL PITCHERS –

Abstract

Using mechanical principles as the basis, the trajectory of a pitched ball is determined by its initial linear and rotational velocities, the angle of release, the direction of the ball’s axis of rotation, and the air density. Among the parameters required to determine the pitched baseball trajectory, ball velocity has attracted the most attention from biomechanics researchers. However, ball velocity is only one aspect of the factors for evaluating the pitching performance. In order to make hitting more difficult for batters, the pitcher introduces spin and alters the trajectory from a simple parabolic trajectory to one in which aerodynamic forces play a significant role. In this paper, relationship between spin, trajectory and the motion will be discussed for fastball and curveball in baseball pitch. In the presentation, softball pitching will be also referred to, so far as time permits.