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Homework Help: Moments of inertia

  1. Feb 15, 2006 #1
    can anyone tell me how to find moments of inertia for the centre point of a semicircle??
  2. jcsd
  3. Feb 15, 2006 #2


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    Do you know the definition of a moment of inertia?
  4. Feb 15, 2006 #3
    Let the mass of the semicircle be M and the radius be R.
    Express the mass of a differentiable element dm in terms of d(theta).
    Then in the actual process of finding centre of mass replace dm by d(theta) of integrting the X-cordinates and Y co-rdinates of the point on the semicircle in terms of theta and dividing the whole with M. I think you know this calculus based procedure to find cenre of mass for continuous objects as asked by TD
  5. Feb 16, 2006 #4


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    There is a very simple method, if you know the MoI of a circle, but to expect help in this forum you must show some effort on your part. Please read the rules for this forum (see my signature).
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