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Homework Help: Momemtum with tennis balls

  1. Oct 19, 2004 #1
    A tennis player swings her 1000 g racket with a speed of 8.00 m/s. She hits a 60 g tennis ball that was approaching her at a speed of 11.0 m/s. The ball rebounds at 36.0 m/s.

    1)How fast is her racket moving immediately after the impact? You can ignore the interaction of the racket with her hand for the brief duration of the collision.

    2)If the tennis ball and racket are in contact for 9.00 ms, what is the average force that the racket exerts on the ball?

    is this a momentum problem where i figure out the p_initial and then p_final and subtract final from initial? and then solve for velocity after from the p_final? and im not sure for the second question. thanks in advance for your help.
  2. jcsd
  3. Oct 19, 2004 #2
    As you suggested, the first part looks like a conservation of momentum question. The second part deals with impulse.
  4. Oct 19, 2004 #3
    ok i got a little farther... basically i set it up like m_r*v_r + m_b*v_b = m_r2*v_r2' + m_b2*v_b2'. where m_r is the mass of racket v_r is velocity of racket m_b is mass of ball and v_b is velocity of ball and same for other side except they are the final values. i am given all of the values except for v_r2' and i tried solving for it but i get a wrong answer. for the second part i just did accel = (v_b' - v_b)/t and then F=ma. but i am confused as to which mass to use because using the racket's mass gave me a wrong answer.
  5. Oct 19, 2004 #4
    nevermind i got it
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