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Homework Help: Stability and moment of inertia

  1. Feb 13, 2009 #1
    The problem and my work is below....I believe I got the problem to work out. The only question I had was if I found the LEAST moment of inertia which is whats needed for the formula at the end of my calculations. What exactly is meant by the least moment of inertia?

    http://i674.photobucket.com/albums/vv106/jason03_2009/prob7-1.jpg [Broken]

    http://i674.photobucket.com/albums/vv106/jason03_2009/prob7-2.jpg [Broken]
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Feb 13, 2009 #2


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    You have calculated the least (minor axis) moment of inertia by assuming the 4 feet as your 'b' and 2 feet as your 'h'. The major axis moment of inertia is much greater ( using 2 feet as the 'b' and 4 feet as the 'h'); hence, the wall is much less stable along the weak axis, and thus, the least moment of inertia applies.
  4. Feb 13, 2009 #3
    ok I see.... so if the rectangle was rotated than the major axis would be calculated with the base being 2 and height being 4.
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