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Homework Help: Finding the tension in a rope attached to a gate underwater.

  1. Nov 14, 2016 #1
    1. The problem statement, all variables and given/known data

    2 & 3. The attempt at a solution
    I've worked out:
    The total force on the gate.
    I have worked out the centre of pressure which I got a value of 10/3m (from the hinge).
    For the moment about the hinge I got a value of 981,000Nm using the equation M=FN*X where X is the centre of pressure and FN is the total force on the gate. Dividing this by 5 (length of gate) I get 196,200N, which I assume must be T?

    (Or T*cosθ which gives me 117,720N, which seems to small)
  2. jcsd
  3. Nov 14, 2016 #2
    Acutally, if I work out the moment M due to the force dFN * the centre of pressure (metres from hinge), and equate this moment to the moment due to T:


  4. Nov 14, 2016 #3
    Sorry, or do I equate the moment 294,300(10/3) in the downwards direction then it will equal T? So 294,300*(10/3)*(3/5)=T(5). So T=117,720N
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