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Average power input

  1. May 2, 2009 #1

    lzh

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    1. The problem statement, all variables and given/known data
    A wheel with rotational inertia I is mounted on a fixed motionless axle. The singular speed w of the wheel is increased from 0 to Wf in a time interval T.
    Net torque=IWf/T

    What is the average power input to the wheel during this time interval?

    2. Relevant equations
    P=torque*angular velocity


    3. The attempt at a solution
    P=(IWf/T)*Wf=(IWf^2/T)
    This isn't right though, what am I doing wrong?
     
  2. jcsd
  3. May 2, 2009 #2

    diazona

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    Homework Helper

    Think about this: what's the power input at t = 0? Or at t = T/2? Or generally, at any time between 0 and T? You only calculated the power input at one particular time, but the problem asks for the average.
     
  4. May 2, 2009 #3

    lzh

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    I was thinking of finding the integral of the power from 0 to T and then divide everything by T. But for some reason the answer is coming out weird.
     
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