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Homework Help: Angular acceleration and power

  1. Nov 21, 2009 #1
    1. The problem statement, all variables and given/known data
    See the image attached
    What power must be applied to this object to accelerate it from rest to an angular speed of 2.7 rad/s in 5.2 s about the x axis?

    2. Relevant equations
    P = W / t - torque * angular velocity

    3. The attempt at a solution
    P = [(0.5 m)*(7 kg)*(acceleration)] * 2.7 rad/s
    I don't know how to find acceleration or if I am doing this wrong all together. The right answer is 1.3 W. I tried plugging it into the motion equation v = vo + at to get a, that gave me the wrong answer.

    Attached Files:

  2. jcsd
  3. Nov 21, 2009 #2


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    Homework Helper

    The work goes into making the system have kinetic energy. Your starting point should be P = KE/time. Now you just have to figure out how much rotational kinetic energy it has when ω = 2.7 rad/s.
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