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Homework Help: Momentum and Impulse for a flywheel

  1. Nov 19, 2007 #1
    Hey. Just wondering if I could get a little help with this quest please.

    A flywheel has a moment of inertia of 854kgm^s, and is allowed to come to rest from and angular velocity of 450rpm. Knowing that kinetic friction produces a resisting moment of magnitude 14Nm, determine the time required for the flywheel to come to rest.

    well, i know that 450x(2pi/60) = 47.12 rad/min = 0.785rad/sec
    so 0.785 is the intial angular velocity..

    but am not sure where to go from here.
    Could someone point me in the right direction please?
  2. jcsd
  3. Nov 19, 2007 #2


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    Homework Helper

    Moment of inertia of the flywheel and torque on it is given. From thewse values find the angular retardation alpha, which is equal = torque/I. Then using kinematics find the time.
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