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Homework Help: Finding force exerted by a rope and ratio of tension:weight

  1. Oct 2, 2011 #1
    1. The problem statement, all variables and given/known data

    A 72.8 kg ice skater is moving at 5.01 m/s when she grabs the loose end of a rope, the opposite end of which is tied to a pole. She then moves in a circle of radius 0.765 m around the pole.

    The acceleration of gravity is 9.8 m/s2 .
    Find the force exerted by the rope on her arms.
    Answer in units of kN = 2.3886108 kN

    Find the ratio of this tension to her weight.

    2. Relevant equations

    Fc = mv^2 / R
    W=mg

    3. The attempt at a solution

    Fc = mv^2 / R
    Fc = (72.8)(5.01)^2 / .765
    Fc = 2388.6108 N
    Fc = 2.3886108 kN

    It's the ratio that's getting me, shouldn't it just be:
    2.3886108 kN / (72.8 x 9.8)
    =.003348

    But the ratio is wrong?

    Please help.
     
  2. jcsd
  3. Oct 2, 2011 #2
    The ratio is a comparison of two forces. But they must be in the SAME units!
     
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