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Homework Help: Center of mass problems!

  1. Nov 18, 2008 #1
    A uniform spherical shell of mass 9.00 with diameter 54.0 has four small masses of mass 2.00 attached to its outer surface and equally spaced around it. This combination is spinning about an axis running through the center of the sphere and two of the small masses yf_Figure_10_43.jpg

    What friction torque is needed to reduce its angular speed from 80.0 to 55.0 in a time interval of 35.0 ?
  2. jcsd
  3. Nov 19, 2008 #2


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    Welcome to PF!

    Hi thecombover! Welcome to PF! :smile:

    Circular version of good ol' Newton's second law …

    net torque = rate of change of angular momentum …

    so how much angular momentum do you need to change? :wink:
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