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Help! Midterm tomorrow! Pulley, Newton's Laws Problem

  1. Sep 1, 2014 #1
    1. The problem statement, all variables and given/known data
    An object consists of 3 connected masses as seen in the figure. None of the surfaces have friction except the surface on m1 which has the coefficients μs=0.4 y μk=0.3.
    What is the acceleration of each one of the masses?
    It looks like the following image but m1 is the table and m2 is equal to m3 or the block thats hanging from the pulley of the table.
    nMkXx.png




    2. Relevant equations
    ∑Fx = m1a → τ - fk = m1a
    ∑Fy = 0 → n- m1g = 0
    T= μkm1g+ m1a
    ∑Fy = m2a → m2g - T =m2a
    m2g - (μkm1g+m1a) = m2a
    a = m2 - μkm1/m1 + m2



    3. The attempt at a solution
    I got up to the finally equation but I can't figure out how to solve the equation without mass. Thanks!! :smile:
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 2, 2014 #2

    BvU

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    Good luck with your test! Post is now incomprehensible, but what the heck.
     
  4. Sep 2, 2014 #3

    PhanthomJay

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    The masses are equal , call them m. But your last equation solving for "a" has algebra errors. Correct your algebra....maybe you don't need to know m.
    If I interpret your problem correctly, wording is confusing.
     
  5. Sep 2, 2014 #4

    Doc Al

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