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Homework Help: Kinetic Friction Problem

  1. Oct 13, 2006 #1
    I am very confused about this problem. The given info is:
    You are standing at the bottom of an 8 m long ramp that is incline 37 degrees to above the horizontal. You grab a package from a conveyer belt and push it up the ramp. The coefficient of kinetic friction is 0.30
    The questions:
    1. What speed do you need to give the package at the bottom of the ramp so it has zero speed at the top?
    2. If the person does not grab the package at the top of the ramp and it slides back down what speed will it return to you?

    So far I have drawn a free body diagram w/ x axis parallel to the incline.
    I have sum(F(x))=F-mgsin37-F(f)=ma
    I get F=-1.93*m+1.3*N
    How do I solve for acceleration? Where do I go from here?
  2. jcsd
  3. Oct 13, 2006 #2

    Doc Al

    User Avatar

    Staff: Mentor

    What's "F"? There are only two forces acting on the package parallel to the ramp. Hint: Express friction in terms of the normal force.
  4. Oct 13, 2006 #3
    Ah ha! I see, it makes a lot more sense now! Thanks!
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