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Homework Help: Uniform Circular Motion Question

  1. Feb 7, 2007 #1
    1. The problem statement, all variables and given/known data:
    A body of mass 81.7g is moving in a circular path of radius 0.65m. If we calculate the centrifugal force on it to have a magnitude of 0.35N, what is the period of revolution? (2 decimals, UNITS!)(p = 3.14)

    2. Relevant equations:
    I'm given the following equations:
    a = v^2/r
    v = Circumference/Period = 2pi/T
    a = 4pi^2r/T^2
    F = Mg
    F = ma
    3. The attempt at a solution:
    I took .35 = mv^2/r so .35 = 81.7v^2/.65 so v = .5276
    then I took T = 2pir/v so T = 2pi(.65)/.5276 so T =7.736

    I got this wrong when I entered it. I may have rounded wrong at the end or didn't do it right in the first place Any help would be appreciated.
  2. jcsd
  3. Feb 7, 2007 #2


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    Homework Helper

    The supplied mass is in grams.
  4. Feb 7, 2007 #3
    so I would divide the mass by 1000 then do what i did?
  5. Feb 7, 2007 #4


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    Gold Member

    Seems that way. Always take note of the units in questions and remember that standard formula are for SI units.
  6. Feb 8, 2007 #5


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    Yes. The S.I. unit of mass is kilograms.
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