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Old 09-20-2012, 11:06 AM   #28
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Join Date: Sep 2010
Posts: 1,993

I hope the following pictures can resolve this dispute.

Figure 6. Arm and racquet motions around contact

The fig.6 demonstrates that tip of the racquet moves upward and to the right. The frame #4 is contact point. The arm pronation, wrist flexion, arm and body forward rotation move the racquet to the right and create flat component VF of the racquet velocity VR, see fig.7. The wrist ulnar deviation and elbow flexion move the racquet upward and produce topspin component VTopspin. I ignored horizontal spins, because they are not essential here.

Figure 7. Ball’s trajectory after impact

So, velocity of the racquet VR is facing up and to the right, not downward. The flat component VF is directed downward and to the right.

However, why the direction of the ball VB does not coincide with racquet velocity direction VR? The fact is that some of the energy of VTopspin is spent on topspin production.

About vectors and their components see
Anatoly Antipin - one of the most delicate tennis players in the world.

Last edited by toly; 10-01-2012 at 08:14 AM.
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