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Homework Help: Torque and Angular Acceleration

  1. Nov 22, 2009 #1
    The pulley shown in the illustration has a radius of 2.70 m and a moment of inertia of 39.0 kg∙m2. The hanging mass is 4.20 kg and it exerts a force tangent to the edge of the pulley. What is the angular acceleration of the pulley?

    All I have so far is the force exerted on the pulley by the block

    mg = 4.2kg * 9.8m/s2 = 41.16N

    which means it exerts a torque of r * F = 2.7m * 41.16N = 111.13Nm

    I know net torque = moment of Inertia * angular acceleration, but I think I am missing another component of the net torque. What is that component and how do I find it?

    Attached Files:

  2. jcsd
  3. Mar 29, 2010 #2
    damnit I'm working on this same problem right now... having the SAME issue ><
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