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Homework Help: Frictional Forces and Coefficients of Friction [Need help!]

  1. Sep 21, 2009 #1
    1. The problem statement, all variables and given/known data
    A sled is pulled at a constant speed over a horizontal surface where the kinetic coefficient of friction is .20. What is the minimum force necessary to keep the sled moving if its mass is 2 slugs?

    2. Relevant equations

    f(s)=U(s)N or f(s)=Ns(mg)

    F(s)= Frictional Force
    (Not sure about this equation or problem)

    3. The attempt at a solution

    F(s) = Ns(mg)
    F(s) = (.20)(2 slugs)(32 ft/s^(2))
    F(s) = 12.8 N ???

    Am I doing this right or wrong? Can somebody please show me how to do this?
  2. jcsd
  3. Sep 22, 2009 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    You did it right, except that the force units are not Newtons.

    What force units go with feet, slugs, and seconds?
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