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Homework Help: A wagon wheel and inertia

  1. Oct 27, 2004 #1
    A wagon wheel 1.00m in diameter consists of a thin rim having a mass of 7.25kg and six spokes each having a mass of 1.30kg. Determine the moment of inertia of the wagon wheel for rotation about its axis.

    I thought that I could simply sum the masses (7 of them) and the multiply them by them by the radius squred. Didnt work!

    I am having some problems with this chaper on rotational dynamics and torque. If anyone knows of any really good books or websites that could be helpful please let me know. Thanks!
  2. jcsd
  3. Oct 27, 2004 #2


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    You cannot simply multiply the masses by the square of the radius to find their moment of inertia. Calculate (by integration) or look up the moment of inertia of a thin rod then apply the parallel axis theorem for moments.
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