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Homework Help: Newton's 2nd Law

  1. Oct 14, 2008 #1
    1. The problem statement, all variables and given/known data
    A tennis player strikes a tennis ball of mass 56.7 g when it is at the top of the toss, accelerating it to 68.0 m/s in a distance of 0.0250 m. What is the average force the player exerts on the ball? Ignore any other forces acting on the ball.

    2. Relevant equations
    f = ma
    a = (f-mg)/m

    3. The attempt at a solution
    This problem was under newton's 2nd law in my textbook and it didn't list any specific equations for average force. I found a few different equations online but I'm unsure on which one to use. Some of them include time and velocity. I'm just not sure on what equation to use for this. I'm guessing you may have to start with a velocity equation because the distance is in the problem?
  2. jcsd
  3. Oct 14, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    The force exerted by the player is the only force you need to worry about. First figure out the acceleration using kinematics. Then apply F = ma.
  4. Oct 14, 2008 #3
    Would you also need to know the time or can you just find the acceleration by using Vf^2=Vi^2 +2ad ??
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