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Homework Help: Frictional force problem

  1. Sep 21, 2008 #1
    Hi all i have a question that i couldn't figure out here is the question.

    1.A block is at rest on the incline. The coefficients of static and kinetic friction are μs = 0.7 and μk = 0.59, respectively. The acceleration of gravity is 9.8 m/s2 .What is the frictional force acting on the 16 kg mass? Answer in units of N

    here is what i did.

    First i try to find the normal force.which is F = M * a

    which equall to N - cos33 * mg = ma
    N - cos 33 * 16 (9.8) = 0 because acceleration is 0.
    then N = 131.50

    After i found normal force I use static friction = μ * N

    which is 0.7 * 131.50 = 92.052.

    Ok then my answer is still wrong so i need some help .

    thank you.
  2. jcsd
  3. Sep 22, 2008 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Re: problem

    What is the component of force down the incline? And therefore how much frictional force opposes it.
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