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Homework Help: Rotation, angular momentum and inertia

  1. Jun 4, 2009 #1
    The rotor of an electric motor has Im= 2 x 10 -3 Kg.m2
    about its central axis. The motor is used to change the orientation of a space probe in which it is mounted. If the axis of the motor is mounted parallel to the axis of the probe (Ip= 12 Kg.m^2) calculate the number of rotations required to turn the probe through 30 degrees about its axis.

    ** I have tried the formula for anuglar momentum and torque here also i have tried to find the ratio between the two bodies but i do not get the correct answer. The answer should be 498 revs but i dont get it right. What else can i try?
  2. jcsd
  3. Jun 5, 2009 #2


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    Homework Helper

    Hi aks_sky! :smile:

    Just use conservation of angular momentum …

    it starts zero, so it stays zero! :wink:

    (and remember 30º = 1/12 of a revolution)
  4. Jun 5, 2009 #3
    sweet.. all sorted.. thank u
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