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Rotational inertia

  1. Oct 18, 2015 #1
    If there is a disk of mass M and radius R that is already rotating, then someone puts a block with mass m on it a meters away from the center of mass.
    What is the rotational inertia then?

    Is it I=(M+m)R^2?
     
  2. jcsd
  3. Oct 18, 2015 #2
    The moment of inertia is additive. The original moment of inertia of the disk should be ##\frac{1}{2}MR^2## and the block's is ##m\cdot (1m)^2## if it's small enough for us to ignore its volume. The answer should be the sum of above.
     
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