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Equilibrium Pulley Tension Problem

  1. Nov 10, 2008 #1
    Hello! I've been trying to understand this one for a while now, and think there might be a general mental block with regards to pulleys, tension etc.
    1. The problem statement, all variables and given/known data
    http://s3.photobucket.com/albums/y5...tions/?action=view&current=pulleyquestion.jpg
    Question: "The system is in equilibrium and the pulleys are weightless and frictionless. The acceleration of gravity is 9.8 m/s^2. Find the tension T. Answer in units of N."


    2. Relevant equations
    w=mg?
    Not really sure about these


    3. The attempt at a solution
    Right, so so far I've tried solving for T2 and T3 separately then solving the big T. Since the pulley on the right has only the 14N mass acting on it, then T2 should be 14N/2, or 7N right? Then for the second pulley on the left, I got
    T3 + T2 - 19 = 0, which would make T3 = 12. Presumably this would make T = 24 N, but this isn't correct!
    I imagine I am making some heinous oversight or massive assumption. Thanks in advance!!
     
  2. jcsd
  3. Nov 11, 2008 #2

    PhanthomJay

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    Science Advisor
    Homework Helper
    Gold Member

    right!
    Tension forces always pull away from the objects on which they act. Correct your error in signage.
     
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