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Homework Help: Work Done by Tension

  1. Mar 25, 2010 #1
    1. The problem statement, all variables and given/known data
    What is the work done per one revolution by tension in a suspended 2m rope with a 150 g tennis ball attached to its end if you swing the rope 2 times a second such that the tennis ball is in a circular trajectory?

    2. The attempt at a solution
    The work done is the force multiplied the distance. I don't understand how the force of the tension in the rope is traveling a distance which makes me think that the work done is 0.
  2. jcsd
  3. Mar 27, 2010 #2


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    Welcome to PF!

    Hi cracka97! Welcome to PF! :wink:
    That's right! …

    work done = integral of force "dot" displacement …

    and, for circular motion, the displacement is always perpendicular to to the tension. :smile:
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