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Homework Help: Two skaters of equal mass grab hands and spin

  1. Feb 15, 2015 #1
    1. The problem statement, all variables and given/known data
    On an ice rink two skaters of equal mass grab hands and spin in a mutual circle once every 2.5s. If we assume their arms are each 0.80m long and their individual masses are 55.0kg , how hard are they pulling on one another?

    2. Relevant equations
    ## a_c = \frac {v^2}{R} ##
    ## v = \frac {D}{T} ##
    ## D = 2 \pi R ##

    3. The attempt at a solution
    With R = 0.8, and m = 55kg, I plugged it into ##F = m a = m \frac {v^2}{R} ## and I got the right answer. However, I don't understand why I have to use m = 55kg, rather than 110 kg (as there are two people spinning).
    Last edited: Feb 15, 2015
  2. jcsd
  3. Feb 15, 2015 #2


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    Because the force acts on each. Each applies a force ##m \frac {v^2}{R} ## to the other, where m is the mass of one.
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