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Homework Help: Finding Net Force with the Coefficient of Friction

  1. Dec 14, 2009 #1
    1. The problem statement, all variables and given/known data
    A 51kg child goes down a 42 degree slide. What is the normal force on him? If the coefficient of friction is .10, what is the net force on him? How far down does he slide before reaching 2.5 m/s?

    2. Relevant equations

    Fk = μFn
    F = ma

    3. The attempt at a solution

    Fn = 51gcos(42)
    = 379 N

    I have no idea what to do to find the net force.
  2. jcsd
  3. Dec 14, 2009 #2


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    Homework Helper

    the component of the child's weights acts down the plane. Friction acts up the plane.

    Also for a normal force N, the frictional force is given by μN.

    Can you find the resultant force now?
  4. Dec 14, 2009 #3
    I believe so:
    .10(379) = 38 N

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