テニスラケットの科学（547）
：テニスラケットの科学（545）の補足２
Science of tennis racket (547)
:supplementary information 2 of Science of tennis racket (545) （English version）
● Spin vs Pace
: from Swedish tennis academy (Fig.1)
https://www.facebook.com/photo?fbid=660476576091296&set=a.466621602143462
* pace: speed
Fig-1
● Ratio of spin rate to ball speed: (Fig.2, Fig.3)
・The larger the angle between swing speed and ball speed direction, the greater the proportion of spin rate compared to ball speed.
・The smaller the angle between swing speed and ball speed direction, the lower the proportion of spin rate compared to ball speed, resulting in a solid impact and crushing the ball upon contact.
Fig-2
Fig-3
● If the “swing (head) speed (magnitude and direction)” and the “speed of the incoming ball (magnitude and direction)” are assumed to be the same, the relationship between the inclination (angle) of the racket face at impact and the “amount of topspin” and “post-impact ball speed (magnitude and direction)” can be observed.
If the racket face is slightly tilted forward, it results in a higher amount of topspin.
If the racket face is slightly tilted backward, it results in a higher ball speed.