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I How do you calculate moment of inertia for circle?

  1. Aug 13, 2017 #1
    Hey, not sure if this is the right place to post this, but here it goes. how do you calculate the moment of inertia for a circle that is not at its center of gravity. Im trying to find the moment of inertia for a complex shape made of many circles, and this seems like a good place to start. Forgive me if the answer is simple, because I have spent hours googling this question and have come up empty handed. I would greatly appreciate any help!
     
  2. jcsd
  3. Aug 13, 2017 #2

    mfb

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    Around which axis? In general, with an integral, but sometimes there are some tricks to avoid this, like the parallel axis theorem.
     
  4. Aug 13, 2017 #3
    This is in two dimensional space. So I think the z axis if I understand correctly.
    Edit:
    I also looked at that wiki page, but couldn't apply it in any useful way.
     
  5. Aug 13, 2017 #4

    mfb

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    What is unclear about the Wikipedia page?
     
  6. Aug 14, 2017 #5
    Are you thinking of a reference point in the plane of the circle but not at the center of the circle?

    A circle is a purely geometric figure, and as such, has no cg. It does have centroid; is that what you have in mind?
     
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