Measurements of the horizontal coefficient of restitution for a superball and a tennis ball
Measurements of the horizontal coefficient of restitution for a superball and a tennis ball
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DOI：
10.1119/1.1450571
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发表时间：
2002-05-01
影响因子：
0.9
通讯作者：
Cross, R
中科院分区：
文献类型：
--
作者：
Cross, R
当球倾斜地入射到平面上时，反弹的旋转、速度和角度通常与相应的入射值不同。所有这三个量的测量是使用数码摄像机拍摄的反弹的网球事件与零自旋在几个不同的表面上的各种角度。球形球的最大旋转速率由球在撞击结束时开始滚动的条件决定。在某些条件下，发现球的旋转速度超过了这个极限。如果球或表面由于在平行于表面的方向上的变形而弹性地存储能量，则可以解释该结果。后一种效应是通过比较网球和超级球的弹跳来研究的。理想情况下，超级球的恢复系数（COR）在垂直和水平方向上都是1.0。研究的超级球的COR被发现是0.76在水平方向上，和相应的COR为网球被发现从-0.51到+0.24取决于入射角和滑动摩擦系数。(C)2002年美国物理教师协会。
When a ball is incident obliquely on a flat surface, the rebound spin, speed, and angle generally differ from the corresponding incident values. Measurements of all three quantities were made using a digital video camera to film the bounce of a tennis ball incident with zero spin at various angles on several different surfaces. The maximum spin rate of a spherical ball is determined by the condition that the ball commences to roll at the end of the impact. Under some conditions, the ball was found to spin faster than this limit. This result can be explained if the ball or the surface stores energy elastically due to deformation in a direction parallel to the surface. The latter effect was investigated by comparing the bounce of a tennis ball with that of a superball. Ideally, the coefficient of restitution COR) of a superball is 1.0 in both the vertical and horizontal directions. The COR for the superball studied was found to be 0.76 in the horizontal direction, and the corresponding COR for a tennis ball was found to vary from - 0.51 to + 0.24 depending on the incident angle and the coefficient of sliding friction. (C) 2002 American Association of Physics Teachers.