| 摘要 |
<p>A ball (1) for playing tennis type games in which the ball bounces comprises bouncing ball with a tail (2); the ball (1) having experimentally determined parameters regarding bounce, diameter, mass, density and air penetration factor; and the tail (2) constituted by one or more, and preferably two or more, lengths of flexible material having experimentally determined parameters of flexibility rating, length, mass, and thickness. <IMAGE></p> |
