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Homework Help: Uniform Circular Motion - Finding Fc/Ft without mass

  1. Jan 31, 2013 #1
    1. The problem statement, all variables and given/known data
    A boy ties a rock to a 0.95 m string and swings it in a horizontal circle directly over his head so that it completes one revolution every 0.75 s. What is the tension in the string?
    So we know r and we can calculate V, but that's all I can deduce

    2. Relevant equations

    3. The attempt at a solution
    2*pi*.95/.75= 7.9587 m/s
    That's how far I got. I know the masses cancel with ma=mv^2/r but then I end up finding the acceleration. Help?
  2. jcsd
  3. Jan 31, 2013 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    I think you need m.
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