Abstract
Trajectories of the billiard balls have long been assumed to behave as the collision of mass points. As a matter of fact, the beginners can enjoy the games with this simple assumption. On the contrary, the professional players know the differences from the theory by their plentiful experiences and adjust them by intuitions. In order to investigate the mechanisms of the differences from the theory and to quantify them under various circumstances, the authors of this study have visualized the movements of the balls by the high-speed camera and have investigated the trajectories quantitatively by using the digital image processing techniques. As a result, velocity, momentum and kinetic energy before and after the collisions between ball and rubber cushion and between ball and ball have been measured. Moreover, the evidence of “throw”, which is one of the typical discrepancies from the theory, has been shown quantitatively.
