CHANGES OF BALL SPIN DURING FLIGHT OF KICKED SOCCER BALL

Abstract

INTRODUCTION: Flight trajectories of balls are changed by the lift force, which closely relates to the direction and rate of the ball spin. It was reported that soccer balls decelerate 20-28% after 20m flight (Bray and Kerwin 2003), while there has been no study about the changes of the direction of the spin axis and the spin rate of soccer balls in flight. The purposes of this study were to investigate the changes of the direction of the spin axis and the spin rate of the soccer ball in the flight, and to obtain a basic knowledge about the flight of kicked soccer balls.