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Homework Help: Coefficent restitution

  1. Dec 6, 2014 #1
    1. calculate the coefficient of restitution when a player hits a ball traveling into a racket at 10m/s and the racket is stationary before the ball hits it. after the ball hits it, the ball has a velocity of 5m/s and the racket is moving in the opposite direction at 1 m/s

    (Velocity before a - velocity before b)/(Velocity after a - velocity after b)
    I know this is whats used to get the answer normally, but im getting the wrong answer (above 1).

    I think it has something to do with racket going opposite direction but not sure what to do?
  2. jcsd
  3. Dec 6, 2014 #2

    Doc Al

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    Staff: Mentor

    You have that a bit backwards (or upside down). You want the relative speed after the collision over the relative speed before the collision.
  4. Dec 6, 2014 #3
    cheers, poor mistake
  5. Dec 6, 2014 #4


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    Science Advisor
    Homework Helper
    Gold Member

    ... and the sign reverses.
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