本研究旨在於比較不同直徑大小桌球，在不同擊球速度、旋轉速下的飛行路徑。 研究方法是運用旋轉球體的流體力學原理及數值方法進行分析。結果發現：一、小球與大球 （以下直徑 38mm 的桌球簡稱為小球，直徑 40mm 的簡稱為大球）的恢復係數分別為 0.875 和 0.867 （桌球規則，民 89；民生報 89/2/24 ）。 二、大、小球假設以旋轉速度 50 轉 ╱秒， 運動速度由 0 公尺╱秒增加到 20 公尺╱秒擊出，則大、小球所受到的空氣阻力（ drag force ），及麥格拉斯力（ Maguns force ）皆隨著速度的增加而遞增， 但運動速度 增加到 15 公尺╱秒至 20 公尺╱秒時，麥格拉斯力的力量曲線遞增速率趨於緩慢，整個過 程中亦發現，大球所受到的空氣阻力，及麥格拉斯力皆比小球大。三、在相同的擊球速度、 高度下，不管是上旋球、無旋球或下旋球，小球的飛行距離皆比大球遠。

　　　　　The purpose of this study was to compare the flying route of small tale tennis balls with that of large ones under different initial velocity and spin speed. The research method was to make analysis by the laws of Fluid mechanics and Numerical methods. The results showed that 1. the coefficients of restitution were 0.875 and 0.867 respectively for small and large balls (those with the diameter under 38mm are called small balls, while those with the diameter 40 mm are large balls), 2. Supposing the balls were hit with the spin speed 50 rev/s, and the velocity increased from 0 m/sec to 20 m/sec, then both their Drag force and Maguns force would increase with the speed. However, when the velocity ranged from 15 m/sec to 20 m/sec, the increasing rate of the Maguns force curve would decline. Another finding is that large balls endured bigger Drag force and Maguns force than small ones, 3. Whether the balls were top-spinning, no-spinning, or bottom-spinning, with the same and height, the flying distance of small balls was longer than that of large ones.