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Friction force problems

  1. Sep 30, 2005 #1
    Direction of friction force is oppose relative motion of the surface .
    What is relative motion of the surface mean and how to identify the direction of the relative motion of the surface .
     
  2. jcsd
  3. Sep 30, 2005 #2

    Doc Al

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    Staff: Mentor

    Friction forces always oppose slipping of the surfaces. When sliding does occur, it's easy to find the direction of the friction. If surface B exerts friction on surface A, then you can find the direction of the friction force on A by viewing things from the reference frame of B. If A moves to the left with respect to B, then the friction force on A acts to the right. (Of course, the friction force that A exerts on B is equal and opposite to the friction force that B exerts on A.)
     
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