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Finding Force of Friction - Tug of War Problem

  1. Mar 28, 2012 #1
    1. The problem statement, all variables and given/known data
    Joe and Bill are playing tug of war. Joe is pulling with a force of 200 N. Bill is simply hanging on, but skidding toward Joe at a constant velocity. What is the force of friction between Bill's feet and the ground?

    A) Greater than 200N but less than 400N
    B) Less than 200N
    C) 400N
    D) 200N

    2. Relevant equations
    [Kinetic Frictional Force] = μkF


    3. The attempt at a solution
    Since Joe is pulling with a force of 200N and there is no acceleration (constant velocity), the net force is zero. The kinetic frictional force should be equal to 200N.
     
  2. jcsd
  3. Mar 28, 2012 #2
    Yep, you got it. Whenever you're presented with one of these problems involving Newton's second law, the best thing to do is to draw a free body diagram and think of the net force on the object. It looks like that's how you went at this problem, so keep it up!
     
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