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Homework Help: Centrifugal force and friction

  1. Sep 15, 2007 #1
    1. The problem statement, all variables and given/known data
    A bug crawls outward from the center of a CD spinning at 200 revolutions per min. The static friction coefficient is 1.2 between the bug and cd. How far does the bug get from the center before slipping? https://www.physicsforums.com/Nexus/editor/menupop.gif [Broken]
    https://www.physicsforums.com/Nexus/editor/menupop.gif [Broken]

    2. Relevant equations
    a = ((2*pi)/T)^2*r //where T is number of seconds it takes to complete a revolution.
    f <= "mu"*N // static equation.

    3. The attempt at a solution
    I started out by trying to find f by using "mu" * g and then trying to solve for r when i have f. So that f = "mu"*a , where a = ((2*pi)/T)^2*r. I don't know if im even on the right track.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Sep 16, 2007 #2
    Centrifugal force experienced by the bug when it is at a distance r fron the centre =
    m(2*pi)/T)^2*r ( m = mass of the bug).[This force increases as r increases]

    Friction force acting on the bug = mu*mg [This force remains constant]

    Equate the above two (m gets cancelled out) and solve for r. You are on the right track.
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