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Homework Help: Two blocks against a wall.

  1. Aug 21, 2014 #1
    1. The problem statement, all variables and given/known data

    There are two blocks against a wall on a frictionless table. I can't really manage a diagram, so please imagine this. There are two blocks, one of 5 kg and another of 10 kg, against each other. The 10 kg one is touching the wall.

    The frictional coefficient between the two blocks is 0.2

    A force of 200 N is applied to the 5 kg block. What is the reactional force?

    2. Relevant equations

    Newton's laws and Frictional force = frictional coef. x Normal

    3. The attempt at a solution

    Should it not be 200 N back? ( The ans. is 177) What role does the friction play here?
  2. jcsd
  3. Aug 22, 2014 #2


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    which direction does the 100N force act in?
    Static or kinetic friction?
    Any friction between block and wall?
  4. Aug 22, 2014 #3
    200 N force acts towards the wall. Static friction. No friction between block and wall.
  5. Aug 22, 2014 #4


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    And perpendicular to the wall? If so, I agree the reaction should be 200N. I strongly suspect you have not described the problem correctly.
    Have you posted the statement of the problem exactly, word for word?
    If there is an accompanying diagram, why can't you post it? Do you need a scanner?
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