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Homework Help: Calculate the angular momentum

  1. Apr 1, 2014 #1
    1. The problem statement, all variables and given/known data
    A batter swings a 0.9 m long bat. Calculate the angular momentum of the bat relative to its axis of rotation. Assume the bat has a mass of 0.6 kg and rotates at 3 rad / s
    (Hint: Approximate the bat by a rod, or a long thin cylinder, and find the moment of inertia.)
    Answer in (N m)

    2. Relevant equations

    3. The attempt at a solution
    so L=(0.6)(.9^2)(ω)
    ω=angular velocity is 3 rad/s
    so L=(.6)(.9^2)(3rad/s)= Wrong answer
    Last edited: Apr 1, 2014
  2. jcsd
  3. Apr 2, 2014 #2


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    Homework Helper

    Hey, welcome to physicsforums!
    uh, the moment of inertia formula you have used is not correct for this problem. The inertia I=(0.6)(0.9)^2 would suggest the mass of the bat is concentrated at the end of the bat. But it looks like they want you to assume the bat is a long thin cylinder, of uniform density. So either you can look up the moment of inertia for this kind of object, or derive it yourself, if you have time.
  4. Apr 2, 2014 #3
    I got it I was using the wrong formula.
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