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Homework Help: Moment of Inertia of a Pyramid

  1. Sep 8, 2008 #1
    1. The problem statement, all variables and given/known data
    Ok not really a school problem but i was just thinking of how to solve it.

    How would i find the moment of inertia of a pyramid with base side length l and height h?
    If the axis of rotation is along the z axis?

    2. Relevant equations

    I = Summation of mrsquared

    3. The attempt at a solution

    Ok so my approach is to find the geometrical center of the pyramid first.

    I would know its easy to cut each of the diagonal lengths by 2 and drawing a straight perpendicular line down, but i wanted to try some integration because i just learned it a week ago.
    I had problems setting up the integral, so could anyone give me a hint or 2?
  2. jcsd
  3. Sep 8, 2008 #2


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    I would start by finding the moment of inertia of a triangular cross section of the pyramid at height z and thickness dz and then integrate that.
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