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Homework Help: Moment of Inertia

  1. Nov 2, 2005 #1
    Hi everybody.
    I'm a newbie here.
    I'm a Physics student at University of São Paulo in Brazil (I'm in 1st year) and find this forum was a very nice surprise for me. I think this is the best thing about Physics in all web and I would like give all of you my congratulations.
    Well, my doubt is about Moment of Inertia.
    I need calculate the moment of inertia for a conic disc with a hole in the center according the figure below. I made several searches on Internet and didn't find nothing about this.
    The diametral section of the ring is like following:
    http://img178.imageshack.us/img178/7999/discocnico013ai.jpg [Broken]
    Thank you very much.
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Nov 2, 2005 #2

    Doc Al

    User Avatar

    Staff: Mentor

    set up the integral

    Realize that the contribution of a given mass element to the moment of inertia is [itex]r^2 dm[/itex]. Hint: Treat the object as composed of a set of concentric rings. Write "dm" for these rings as a function of r and the density. Integrate!
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