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Homework Help: Moment of Inertia of a pulley

  1. Apr 1, 2010 #1
    1. The problem statement, all variables and given/known data
    A 1.65 kg mass is attached to a light cord that is wrapped around a pulley of radius 4.65 cm, which turns with negligible friction. The mass falls at a constant acceleration of 2.40 m/s2. Find the moment of inertia of the pulley.

    2. Relevant equations
    I=mr^2
    Torque=I*alpha


    3. The attempt at a solution
    I tried to just square the radius given and multiply it by the mass but that did not work. I also tried to find the Torque using T=mgr. And then divided that number by the acceleration/radius in order to get the angular acceleration.
     
  2. jcsd
  3. Apr 1, 2010 #2

    rock.freak667

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    So what did that give you?
     
  4. Apr 1, 2010 #3
    It gave me the wrong answer. I guess that is not the correct way to find the torque
     
  5. Apr 1, 2010 #4

    rock.freak667

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    That should be the correct way to do it, post your work.
     
  6. Apr 1, 2010 #5
    I figured it out using a different set of equations. Thanks for your help though, sorry to waste your time.
     
  7. Apr 1, 2010 #6

    rock.freak667

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    What equations did you use by chance?
     
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