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Homework Help: Frictional Torque Flywheel Question

  1. Apr 8, 2009 #1
    1. The problem statement, all variables and given/known data

    A spinning flywheel has rotational inertia I = 403.8 kg · m2. Its angular velocity decreases from 20.0 rad/s to zero in 256.8 s due to friction. What is the frictional torque acting?

    3. The attempt at a solution

    I tried using Vt = r |w| and Wav = change in theta / change in time, to get r, but I'm not sure if that's right,

    Then I used I = 1/2mr^2 to get mass.

    Finally, I used F=ma to get Force, using the mass found above and acceleration = change in velocity (aka 20*57) / change in time.

    Then I had force and radius for plugging into torque = radius*force.
  2. jcsd
  3. Apr 8, 2009 #2


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    Homework Helper

    Using w = wo + alpha*t, find alpha.
    Torque = I*alpha.
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