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Homework Help: What is the angular momentum of the record?

  1. Nov 8, 2009 #1
    1. The problem statement, all variables and given/known data
    A .019 kg record with a 15 cm radius rotates with an angular speed of 33 1/3 rpm. What is the angular momentum?

    2. Relevant equations
    L=Iw I=mr^2 w=(33.33/60)*2pi=3.17 rad/s

    3. The attempt at a solution
    but thats wrong, and i dont know why
  2. jcsd
  3. Nov 8, 2009 #2


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    Homework Helper

    Check your calculation of your conversion to rad/s, I get a different number. Also, check that you are using the appropriate formula for the moment of inertia. Are you assuming the record is a solid disk? If so, your formula for I is not quite right.
  4. Nov 8, 2009 #3
    thanks i figured it out, i accidently udes 30.33, not 33.33, and i found the right equation
    I=.5mr^2, and the right answer is 7.5x10^-4, thanks for your help
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