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Finding natural force and friction coefficient

  1. Oct 21, 2007 #1

    lim

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    1.
    [​IMG]

    The problem statement, all variables and given/known data

    A. Refer to the sketch below to answer the next two questions. Force P (139.75 N) pulls on a crate of weight W (196 N) on a rough surface at a constant speed. The figure shows the directions of the forces that act on the crate. FN represents the normal force. The kinetic frictional force is f (63.23 N). The angle, a, is 63.1 degrees. Calculate the value of the normal force.

    B.Find the coefficient of kinetic friction.


    2. Relevant equations
    (friction) f= MN
    Natural force= weight (N=W)


    3. The attempt at a solution
    N=W
    N= 196(9.8)
    N= 1920.8 N

    63.23= M(1920.8)
    M= 0.0329


    Any ideas?
     
  2. jcsd
  3. Oct 21, 2007 #2

    hage567

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    Homework Helper

    Since force P is acting at an angle, there is both a vertical and horizontal component to it. You must consider each of those in their respective direction when you sum up the forces according to Newton's second law. So, the normal force will not be just m*g, it will have a term based on the vertical component of P. Do you know how to resolve a vector into its components?
     
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