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Homework Help: Moment of inertia of a disk

  1. Nov 5, 2011 #1
    1. The problem statement, all variables and given/known data
    What is the moment of inertia of an 8 kg, 40 cm diameter disk for rotation through the edge of the disk?

    2. Relevant equations
    [tex]I = \frac{1}{2}MR^2[/tex]

    3. The attempt at a solution

    Inertia at the center of the disk would be [tex]I = \frac{1}{2}MR^2[/tex], right? I'm not sure what the right equation for inertia at a point on the edge of a disk would be.
  2. jcsd
  3. Nov 5, 2011 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    Apply the parallel axis theorem to find the moment of inertia about a parallel axis a distance d from the centre of mass:

    [tex]I = I_{cm} + Md^2[/tex]

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