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Homework Help: Linear Momentum/Impulse Problem

  1. Aug 15, 2010 #1
    1. The problem statement, all variables and given/known data

    A ball with a mass of .2 kg travelling at a speed of 26 m/s is struck by a bat. If the duration of the impulse is .001 seconds and the speed of the ball afterwards is the same as before, what is the average force (to the nearest Newton) of the impact? On the other hand, if the magnitude of the average force is 20000 N, what is the speed to the nearest m/s after collision?

    2. Relevant equations

    Fnett =[tex]\Delta[/tex]p = m[tex]\Delta[/tex]v

    3. The attempt at a solution

    F=(.2 kg)(26m/s-0)/.001 = 5200

    This answer is always 1/2 off the correct answer so I'm not sure if the equation I'm using is wrong or if I'm applying it incorrectly. As for the second question, I'm not quite sure where to go with it.
  2. jcsd
  3. Aug 15, 2010 #2
    Haha I got the answer. It goes back to thinking Kinematics equations where vf=vi+at

    therefore, to get the acceleration you use Newton's second law: F=ma where F= 20000N and m = .2 to get a = 100,000

    vf = vi + at
    vf= 26 - (100,000)(.001)
    vf = -74 m/s
    vf is 74 m/s in the opposite direction it was thrown in

    hope this helps someone else that's stuck
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