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Friction Force exerted on an object

  1. Dec 10, 2015 #1
    1. The problem statement, all variables and given/known data
    A man is exerting a force of 200 N on a refrigerator and pushing the fridge across a rough floor at a constant velocity to the right.
    How much friction force acts on the refrigerator ? Give a number and appropriate units.

    2. Relevant equations

    3. The attempt at a solution
    I think that the friction force exerted by the floor would be equal to the man's exerted force on the refrigerator, but at the same time I know that the force exerted by the man and the friction force exerted by the floor are not an action/reaction pair, so I am not sure that they would be equal.
  2. jcsd
  3. Dec 10, 2015 #2
    Action-reaction pairs have nothing to do with the answer to this problem. Have you drawn a free body diagram on the refrigerator, showing the horizontal forces acting on it?

  4. Dec 10, 2015 #3
    I was given a diagram (below) and told the force exerted by the man on the refrigerator is 200 N. In this case the man is A and the refrigerator is B

    Attached Files:

  5. Dec 10, 2015 #4
    Who says that forces that are not action-reaction pairs can't be equal? I still don't see your free body diagram showing only the refrigerator, with the forces acting on it.
  6. Dec 10, 2015 #5
    If I know that there is no acceleration, can I use Newton's second law to conclude that the friction force is equal to the force enacted upon the fridge by the man?
  7. Dec 10, 2015 #6
  8. Dec 10, 2015 #7
    Thank you!!
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