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Homework Help: Energy lost to friction

  1. Mar 22, 2008 #1
    1. The problem statement, all variables and given/known data
    A spool of thin wire (with inner radius r = 0.40 m, outer radius R = 0.55 m, and moment of inertia I_cm = 0.7139 kg*m^2) pivots on a shaft. The wire is pulled down by a mass M = 1.350 kg. After falling a distance D = 0.550 m, starting from rest, the mass has a speed of v = 65.4 cm/s. Calculate the energy lost to friction during that time.

    im not really sure how to do this. i would like any ideas.
  2. jcsd
  3. Mar 22, 2008 #2

    Doc Al

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    Staff: Mentor

    Consider the change in potential energy.
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