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Homework Help: Work Against Friction

  1. Oct 9, 2007 #1
    1. The problem statement, all variables and given/known data
    You push an object of mass slowly, partway up a loop-the-loop track of radius , starting from the bottom, where the normal force to the track is vertically upward, and ending at a point a height above the bottom. The coefficient of friction between the object and the track is a constant .Find the work you do against friction.

    2. Relevant equations Work against friction= Friction Force x Displacement

    3. The attempt at a solution
    Not how to get the height of the car. I belive that the friction part would simply be (Kinetic Friction)x(Normal Force). But I'm not entirely sure about how to get the normal force either
  2. jcsd
  3. Oct 9, 2007 #2


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    Welcome to the forums Darth,

    In what direction (relative to the surface) does the normal force act?
  4. Oct 9, 2007 #3
    I think that it acts towards the center of the loop
  5. Oct 9, 2007 #4


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    Do they give any numbers or variables?
  6. Oct 9, 2007 #5
    No, no numbers are given
  7. Oct 9, 2007 #6
    the variables are m-mass Radius-R an ending point of h<R and the coefficient of friction is u
  8. Oct 9, 2007 #7


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    Suppose theta is the angle the surface forms with the horizontal... what is the normal force in terms of theta. What is the frictional force?
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