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Moment of Inertia Using Parallel Axis Theorem

  1. Oct 27, 2013 #1
    1. The problem statement, all variables and given/known data

    VlBTZHQ.png

    Q is the edge length of the cube. The moment of inertia of the cube about an axis passing through its center and the center of two opposing faces is (1/6)mQ^2 (PCM in the diagram). Use the parallel axis theorem to find the moment of inertia if the axis is along one face of the cube (Pface).

    PCM=(1/6)mQ^2
    Pface=?
    d=?

    2. Relevant equations

    Pface = PCM+md^2

    3. The attempt at a solution

    d=(1/2)Q^2

    Pface=[itex]\frac{mQ^2}{6}[/itex]+[itex]\frac{mQ^2}{4}[/itex]

    Pface=[itex]\frac{5mQ^2}{12}[/itex]
     
  2. jcsd
  3. Oct 27, 2013 #2
    Correct...except d = Q/2
     
    Last edited: Oct 27, 2013
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