Coefficient of restitution of a baseball bat is not a set quantity, but it is altered as angular and translational swing velocities and the point of impact are changed

2017 Fiscal Year Final Research Report

• Project/Area Number: 26282177
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Sports science
• Research Institution: Waseda University
• Principal Investigator: Yanai Toshimasa 早稲田大学, スポーツ科学学術院, 教授 (50387619)
• Research Collaborator: Kidokoro Shuji ; Miyazawa Takashi ; Shimura Mei
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 野球 / 打撃 / インパクト / 振動特性

Outline of Final Research Achievements

This study revealed that even with the same bat head velocity during a swing, varying combinations of angular swing velocity and translational swing velocity can result in different batted ball velocities, and that a large translational swing velocity results in a greater batted ball velocity than a large angular swing speed. In other words, the point of impact that maximizes batted ball velocity changes based on the combination of angular swing velocity and translational swing velocity. These phenomena occur because (a) the coefficient of restitution of the bat is not a set quantity, but it is altered as angular swing velocity, translational swing velocity and the point of impact are changed and (b) the magnitude and the direction of the linear and angular momenta transferred between the bat and the baseball is altered by varying angular swing velocity, translational swing velocity and the point of impact.

Free Research Field

スポーツ科学（バイオメカニクス）