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Homework Help: Moment of Inertia calculation

  1. Sep 7, 2012 #1
    I'm not sure if this is the right place to ask this, but I'll try here... [I'm not physics student and don't know how to differentiate "intro physics" from "not intro physics"]

    I'm asked to calculate moment of inertia [around center of mass] for a thick disk.
    The problem: I calculate the moment of inertia in two different ways and get different answers.
    Way 1 [the crazy method] - I calculate moment of inertia for some inner part of the disk then I calculate the moment of inertia for the rest of the disk.
    Way 2 [the standard method] - I calculate the moment of inertia of the whole disk continuously.

    The mass of the outer disk is M/2 and so is the mass of the inner disk.
    It is hard to to draw thing in the forums so I'm attaching my drawings and calculations as a picture: link.
  2. jcsd
  3. Sep 7, 2012 #2
    Please delete, I figured it out.
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