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Homework Help: Pulleys and friction

  1. Jun 9, 2004 #1
    Alright, I know I have this stuff somewhere at school, but unfortunately, I can't leave it till tom.

    A mass is at rest on a horizontal plane, and is attached by a second mass that is threaded through a pulley and is suspended in the air. What is the coefficient of friction?

    The formula I've been using is

    M(1)a(coefficient of friction) = M(2) (g-a)
    (sorry about the horrible representation)

    rearranged into this:

    M(2) (g-a) = (coefficient of friction)
    M(1)a

    where a= acceleration
    M= mass
    g = gravity = 9.81

    Unfortunately, upon plugging in my numbers from the experiment, I keep getting 7.5171...for the coefficient of gravity...which to me seems impossibly high!
     
  2. jcsd
  3. Jun 9, 2004 #2
    The system is at rest, so what's acceleration supposed to be?

    cookiemonster
     
  4. Jun 9, 2004 #3
    Oops, forgot to mention that the system BEGINS at rest and then the suspended mass is released, hence the acceleration...wow, I feel dumber already! :uhh:

    Acceleration was 0.6525 m/s(squared)
     
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