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Topspin for a tennis ball to not change velocity while bouncing

  1. Apr 10, 2014 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    Tangential v = wr

    3. The attempt at a solution
    I first drew a force diagram for when the ball contacts the floor.

    Topspin means the ball is moving tangentially backward.
    Therefore, the bottom moves at v - wR. Friction works opposite in the direction of motion, so it will slow it down if v > wR, but it will speed it up if v < wR. Therefore, in order for there to be no change, v = wR, so w = v/R
  2. jcsd
  3. Apr 10, 2014 #2
    You have the right idea .For ω0 = v0/R ,the net horizontal velocity of the bottommost point will be zero .On contact with the surface there will be no slipping ,hence no friction .
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