Factors effecting the lateral deflection of a curving baseball

Abstract

The purpose of this study was to analyze selected variables effecting the lateral deflection of a curving baseball. More specifically, the purposes of this study were to determine the relationship between spin, angle of release, axis of rotation, velocity and lateral deflection and their effects on the trajectory in the horizontal plane of a curving baseball. A total of 12 baseballs, projected by the "Jugs" pitching machine, were filmed using two high speed cameras. A Vanguard Motion Analyzer was used to analyze the film. An initial velocity and initial angle were determined for each throw. Rate of rotation, velocity, and axis of rotation were compared to lateral deflection and angle of deflection for each trial. Correlation coefficients for the relationship were reported. A computer program was developed to predict the trajectory of a curving baseball in the horizontal plane. Axis of rotation, velocity, and rate of rotation were found to have a high relationship with lateral deflection and angle of deflection. The trajectory of a curving baseball was found to curve throughout the path. It was shown that the change in deviation increased as the ball moved along the path of the trajectory. As the velocity of the ball slowed down, the number of spins increased per ten-foot segments. This caused a greater affect on the curvature of the projected baseball. Conclusions. (1) Variables that have a relationship with lateral deflection and angle of deflection are rate of rotation, initial velocity, difference velocity, and axis of rotation. (2) The baseball curves all the way along the path of the trajectory with increasing deviation as it approaches the plate. (3) The computer program is an accurate method of predicting the trajectory of a curving baseball. When the initial velocity, angle of release, accuracy at the plate, side force and drag force are known, it is possible to predict the trajectory of a curving baseball. (4) The number of revolutions and velocity are the variables that have the greatest effect on the trajectory of a curving baseball in the horizontal plane when axis of rotation is relatively stable. (5) There is an inverse relationship between velocity and change in deviation of a curving baseball. (6) There is a direct relationship between number of spins and change in deviation of a curving baseball.