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Homework Help: Momentum of ball bouncing off wall

  1. Oct 11, 2011 #1
    1. The problem statement, all variables and given/known data
    A racquet ball with mass m = 0.247 kg is moving toward the wall at v = 12.4 m/s and at an angle of θ = 32° with respect to the horizontal. The ball makes a perfectly elastic collision with the solid, frictionless wall and rebounds at the same angle with respect to the horizontal. The ball is in contact with the wall for t = 0.063 s.

    2. Relevant equations
    What is the magnitude of the change in momentum of the racquet ball?

    3. The attempt at a solution
    I found the initial P already and am not sure if I should use the (delta)P= F(net)* (delta)t and use 1-d kinematics to find acceleration or how exactly to begin.
  2. jcsd
  3. Oct 12, 2011 #2
    Since the collision is assumed to be perfectly elastic, try using conservation of KE.
  4. Oct 12, 2011 #3
    Then find the change in momentum.
  5. Oct 12, 2011 #4


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    Science Advisor

    Momentum is a vector quantity. The component of momentum parallel to the way will not change. The component of momentum perpendicular to the way is multiplied by -1.
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