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Homework Help: 2 masses connected by a pulley, one on an inclined plane.

  1. Feb 1, 2010 #1
    1. The problem statement, all variables and given/known data
    A mass m2 = 1.9 kg, on a 34.1° incline, is connected to a mass m1 = 6.2 kg, on a horizontal surface. The surfaces and the pulley are frictionless. If F = 21.8 N, what is the magnitude of the tension in the connecting cord? Link to photo - http://i48.tinypic.com/e0l5hk.jpg

    2. Relevant equations
    Fnet = ma

    3. The attempt at a solution
    I've gotten the answer wrong 9 different times so far and I have no clue why. This is my last attempt(ten tries total).

    I've drawn the free body diagrams for both masses, m1 has a positive tension, the force of gravity, and a normal force.
    m2 has a normal force perpendicular to the plane which i think equals Fn = (Fg)cos(34.1). It also has a negative tension which is equal to the other tension on mass two, it has the force F pulling along the x axis. So this is what I have no far

    Box 1 Fnet = T1
    Box 2 Fnet = (21.8N - (fg)sin34.1) i + (fgcos34.1)j

    i have all this information, but i have no clue what to do with it. I've tried dividing the (21.8N - fg(sin34.1) by the total weight, which should give me the Fx acceleration, then multiplying that by the 6.2kg mass to give the tension in the connecting cord but that doesn't seem to work.

    Like I said, this is my last chance to get the problem right so thanks for any help.
  2. jcsd
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