本研究旨在探討網球拍於不同張力狀態下，拍頭固定與未固定受碰撞後，網球拍彎曲或扭曲所耗損之動量－衝量。研究以自由落體方式向心碰撞球拍拍面，並透過攝影及振動分析蒐集振動響應與反彈係數資料，以探討不同網線張力下拍頭固定與未固定振動響應與反彈係數之變化，研究結論如下： 一、不同網線張力狀態下，網球拍拍頭固定與未固定碰撞球時，未固定拍頭網球拍振動響應動量大於固定網球拍拍頭（約差3倍）。 二、不同網線張力狀態下，網球拍拍面於固定與未固定碰撞球時，固定拍頭網球拍反彈係數大於未固定網球拍拍頭（約差3倍係數）。 三、反彈係數50磅張力網球拍大於70磅張力網球拍，而振動響應則反之。

The purpose of the study is to investigate the vibrating impact of racket heads, fixed or unfixed, with different amounts of string tension when striking a tennis ball. A camera and a vibrating-impact reader are employed to record the vibrating impacts and rebound coefficients of a tennis ball falling on fixed and unfixed racket heads with varying amounts of string tension. The findings are listed below: (1) When a tennis ball strikes both fixed or unfixed racket heads with varying degrees of string tension, the vibrating impact of the unfixed racket heads is about three times stronger than that of the fixed ones; (2) Similarly, the rebound coefficients of the fixed racket heads are about three times higher than that of the unfixed ones; (3) The rebound coefficient of a racket with 50 lbs string tension is higher than that of a racket with 70lbs of string tension. However, the vibrating impact is reversed.