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Please help with a question about friction

  1. Aug 19, 2016 #1
    1. The problem statement, all variables and given/known data
    Three blocks A, B, and C of masses m1, m2 and m3 respectively are lying on top of each other on a frictionless table with A on top and C on bottom. The coefficient of friction between A and B is u1 and between B and C in u2. Find the accelerations a1, a2 and a3 of the three blocks if a horizontal force F is applied on:
    (a) A, (b) B and (c) C
    The force F is applied on one block at a time and the accelerations are noted and then it is applied on the second one then the third one giving us three sets of accelerations.

    2. Relevant equations

    3. The attempt at a solution
    I can't get anything in my head.
  2. jcsd
  3. Aug 19, 2016 #2


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    First thing to do is make a drawing. You will notice it's impossible to draw three blocks on top of each other :smile: but you can draw a block C on top of B which is on top of A.
    Then for each case make a free body diagram of each of the blocks. See if you have enough information to solve, or if you still need some additional assumptions (about sliding or not sliding :rolleyes: )

    Oh, and: you can't get started without some relevant equations. That's why there is a section 2 in the template. Check your notes or your textbook.

    The equations link the variables that appear in your diagrams, so make a list of them (item 1 in the template :wink: ).

    By the way, your thread may be deleted by a mentor for not showing any effort. See the guidelines
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