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Homework Help: Two Blocks Connected by a Massless String Over a Pulley

  1. Oct 16, 2012 #1
    A 6.0kg box is on a frictionless 35° slope and is connected via a massless string over a massless, frictionless pulley to a hanging 2.0kg weight. What is the tension in the string if the 6.0kg box is held in place, so that it cannot move?

    m1= 6.0kg
    m2= 2.0kg

    So, for Box 1 to be held in place so that it doesn't move, the net force has to be equal to zero. If we tilt our coordinate system 35°,

    Fnet,x = T + Gx
    0 = T - mgsinθ
    T = mgsinθ
    T = (6.0kg)(9.8m/s2)sin(35°)
    T = 33.726269N

    That's the only way that I can think to do this question. The online assignment is telling me that I'm flat wrong. Is there something that I'm missing?
  2. jcsd
  3. Oct 16, 2012 #2
    Umm, You need to consider the 2 forces affecting the block on the slope, that's where you will get your tension. That is the way I understand it works. The block on the slope will start pulling the 2 kg no matter what, so if it starts moving, it will gain an acceleration and if it gains an acceleration then that means something, don't you think?
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