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Many teach pros advocate hitting a ball with the racket face vertical and swinging from low to high at about 30 degrees (actually Vic Braden is the one who likes to use the the 30 degree angle). However, don't you think pro players (and whoever hits the ball hard) hit the ball with the face with a slight tilt (say about 3 to 5 degrees)? Whenever I hit a backhand with the face almost perfectly vertical at impact and swinging from low to high, the ball goes out. Of course, I can hit it much softer but, of course, it looks less respectable.
My theory: Let F be the magnitude of the force imparted on the ball. The tangential force is F*sin(A), for a vertical racket face impact. The vertical force which sends the ball upward is also F*sin(A). A is the angle of the swing path (roughly 30 degrees). If you tilt the face a little bit then the tangential force, which contributes to the spin, is then F*sin(A + B), with B the tilt angle, which is usually around 3 to 5 degrees. With A at 30 degrees, the value of sin(A) is 1/2. However, the slope of sin (which is cos) at 30 degrees is large; cos (A) is .866. Therefore, by tilting the face slightly, one can increase the spin quite a bit without increasing the vertical force, which stays at F sin(A). If one tilts the angle further than that, the transfer of momentum diminishes drastically because it is not an elastic collision between the racket and the ball.
Based on what you have seen on numerous high speed videos, what do you think?
My theory: Let F be the magnitude of the force imparted on the ball. The tangential force is F*sin(A), for a vertical racket face impact. The vertical force which sends the ball upward is also F*sin(A). A is the angle of the swing path (roughly 30 degrees). If you tilt the face a little bit then the tangential force, which contributes to the spin, is then F*sin(A + B), with B the tilt angle, which is usually around 3 to 5 degrees. With A at 30 degrees, the value of sin(A) is 1/2. However, the slope of sin (which is cos) at 30 degrees is large; cos (A) is .866. Therefore, by tilting the face slightly, one can increase the spin quite a bit without increasing the vertical force, which stays at F sin(A). If one tilts the angle further than that, the transfer of momentum diminishes drastically because it is not an elastic collision between the racket and the ball.
Based on what you have seen on numerous high speed videos, what do you think?
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