Dowell L J, Krebs G
Department of Health and Physical Education, Texas A&M University, College Station 77843-4243.
Br J Sports Med. 1991 Mar;25(1):34-7. doi: 10.1136/bjsm.25.1.34.
The purpose of this study was to develop a formula to determine and compare the compressibility of selected sport balls. Six balls (basketball, volleyball, soccer ball, baseball, handball, golf ball) were dropped ten times from each of four different heights onto a smooth solid surface overlaid with a white sheet of typing paper, overlaid with a sheet of carbon paper. The diameter of the area of contact of each ball imprinted onto the typing paper was measured in millimetres with calipers. From the data, the distance (d) that each ball compressed for each velocity (v) was calculated. It was found that a linear relationship existed between velocity at impact and the distance for each ball studied. The compressibility coefficient (c) for each ball was calculated and a formula was developed to determine the distance each ball would compress at a given velocity. When velocity is measured in metres per second and the distance a ball compresses is measured in millimetres, the formula to determine d for selected balls, in order of compressibility is: basketball d = 3.07v, volleyball d = 2.90v, soccer ball d = 2.80v, baseball d = 0.77v, handball d = 0.53v, and golf ball d = 0.17v.
本研究的目的是开发一种公式，以确定并比较选定运动球的可压缩性。六个球（篮球、排球、足球、棒球、手球、高尔夫球）从四个不同高度分别向覆盖有一张白色打字纸且上面又覆盖有一张复写纸的光滑固体表面掉落十次。用卡尺以毫米为单位测量印在打字纸上的每个球的接触面积的直径。根据这些数据，计算出每个球在每个速度（v）下压缩的距离（d）。研究发现，对于所研究的每个球，撞击时的速度与压缩距离之间存在线性关系。计算出每个球的可压缩系数（c），并开发了一个公式来确定每个球在给定速度下会压缩的距离。当速度以米每秒为单位测量，球压缩的距离以毫米为单位测量时，按可压缩性顺序确定选定球的d的公式为：篮球d = 3.07v，排球d = 2.90v，足球d = 2.80v，棒球d = 0.77v，手球d = 0.53v，高尔夫球d = 0.17v。
