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Homework Help: Centripetal Force (RPM Question!)

  1. Nov 2, 2011 #1
    1. The problem statement, all variables and given/known data
    A coin is placed 18cm from the axis of a rotating turntable of variable speeds. If the coefficient of friction is 0.68, what is the maximum r.p.m that the coin can handle before sliding off?

    2. Relevant equations
    This is basically what I need..
    I know there's mv^2/r
    But which equation do I need for RPM questions?

    3. The attempt at a solution
    None at the moment, not sure of the equation I'm supposed to use :S
  2. jcsd
  3. Nov 2, 2011 #2


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    Homework Helper

    As well as mv2/r there is 4∏2rm/T2 where T = period

    Since frequency is 1/T that would mean 4∏2rmf2

    frequency means revolutions per second. r.p.m is revolutions per minute.
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