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Homework Help: Angular acceleration, rigid body

  1. Dec 4, 2013 #1
    1. The problem statement, all variables and given/known data
    A circular disk with the mass m and radius r is hanging from two ropes with length l when suddenly the rope ED snaps. For this moment, find:

    a, The angular acceleration for the rope OB, the angular acceleration for the disk
    b, The force T acting in OB

    3. The attempt at a solution
    Or lack thereof, really don't know how to approach this without a given ω. I can find some relations between the accelerations at different points but ultimately I'm sitting with a lot of unknowns.
    Frankly don't know how to connect the force acting on the disk to any general acceleration.

    Attached Files:

  2. jcsd
  3. Dec 4, 2013 #2


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    Homework Helper

    You know the angular speed at the instant when rope ED snaps: the disks is in rest.
    The disk is a rigid body: all points have the same angular acceleration and angular velocity. How is the angular acceleration of a rigid body related to other quantities - torque and moment of inertia?

  4. Dec 4, 2013 #3


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    Science Advisor
    Homework Helper
    Gold Member

    So post them.
    What forces act on the disk?
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