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Homework Help: Need help finding μ in Frictional Force equation

  1. Nov 6, 2011 #1
    1. The problem statement, all variables and given/known data
    A crate with a mass of 25 kg is on a ramp that is inclined at an angle of 30o from the horizontal. An applied force of 35 N directed parallel to the ramp is used to pull the crate with a constant speed up the ramp a distance of 15 m. What is the work done on the crate by the frictional force?


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 6, 2011 #2
    What have you tried so far?
     
  4. Nov 6, 2011 #3
    Ffrict = µ • Fnorm-
    Fnorm= 537.5J
    Ffrict=(?)•537.5J
     
  5. Nov 6, 2011 #4
    How did you get to that normal force?


    And what can you say about the forces acting on the block?


    You shouldn't have to find µ to answer this question.
     
  6. Nov 6, 2011 #5
    The question was asking for multiple answers which include;
    1. What is the work done on the crate by the applied force?
    2. What is the work done on the crate by the normal force?
    3. What is the work done on the crate by the gravitational force?
    4. What is the work done on the crate by the frictional force?
    5. What is the total work done on the crate?

    I found everything else except frictional force.

    F=FxD=25x35sin(30)=437.5
    so, Normal Force=437.5J
     
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