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Homework Help: Total Kinetic Energy

  1. Nov 25, 2008 #1
    1. The problem statement, all variables and given/known data
    A man stands at the center of a turntable that can rotate without friction. He then takes a 1.5 kg globe of the earth and swings it around his head at the end of a 0.7 m long chain. The world revolves around him every 3.4 s, and the man and the platform have a moment of inertia of 0.5 kgm^2. The angular velocity is 2.71 rad/s in the opposite direction to that of the globe. What is the total Kinetic Energy of the man, the globe, and the platform?

    2. Relevant equations
    K = 0.5Mv^2 of the globe + L^2/(2I) of the platform

    3. The attempt at a solution
    K total = 0.5Mv^2 + L^2/(2I)
    K total = 0.5(1.5)(0.7x2pi/3.4)^2 + (0.5x2.71)^2/(2x0.5) = 3.091J

    Plz. help... I do not think my answer is right... mainly the equation part...
    -Thanks a lot...
     
  2. jcsd
  3. Nov 26, 2008 #2
    Looks right to me.
     
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