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Rotational power

  1. Oct 18, 2006 #1
    A 32.0 kg wheel, essentially a thin hoop with radius 1.20 m is rotating at 280 rev/min. It must be brought to a stop in 15.0s
    What ist the required average power to do this?

    I know that P=τω
    To find τ I used the equation τ=Fd where F=ma I figured I would find a by using the equation ωf= ωi + αt
    First off is this the right approach? I'm also confused as to what d is. My book doesn't really explain it that well, would d be = 1.20m?

    Thanks for any help
  2. jcsd
  3. Oct 18, 2006 #2


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    Staff: Mentor

    Another way to approach this problem is to calculate the initial rotational energy, then the average power is just delta-E / delta-t

    What is the rotational E in terms of the moment of inertia and rotational velocity? How do you calculate the moment of inertia for the wheel as described?
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