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Homework Help: A rod attached to a wall by a hinge, the rod is also attacked to a cord and a pulley

  1. Nov 28, 2008 #1
    1. The problem statement, all variables and given/known data
    A simple crane consists of a rigid rod that is hinged to a wall at one end and tied to the wall with a horizontal cable at the other end. The rod makes an angle θ to the wall. At the same end to which the cable is attached there is also a frictionless pulley. The rope that is looped over this pulley is attached to a mass m at one end and is held at the other end so that the weight hangs in equilibrium. Given that the gravitational field is g, what is the tension, T in the horizontal support cable?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 28, 2008 #2

    tiny-tim

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    Hi XxseanxX_22@h! :smile:

    Show us what you've tried, and where you're stuck, and then we'll know how to help. :wink:
     
  4. Nov 29, 2008 #3
    Re: a rod attached to a wall by a hinge, the rod is also attacked to a cord and a pul

    well i got mgtanθ
     
  5. Nov 30, 2008 #4

    tiny-tim

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    hmm … that's not even an equation, that's only the component of the weight of the mass m along the rod.

    (btw, what's the mass of the rod itself?)

    Hint: in problems like this, start by saying how many forces there are on the rod, and what they are. :smile:
     
  6. Nov 29, 2010 #5
    Re: a rod attached to a wall by a hinge, the rod is also attacked to a cord and a pul

    I know this is another old post, but I found that XxseanxX_22@h has posted identical problems in the past that I have right now, I'm thinking he was potentially in the same class I am in now xD (btw, it is just coincidence we have the same name :S)

    I am stuck, for net forces I have found that T=sintheta and 2mg=costheta. I'm not sure if those are right, but I'm also having trouble finding net moment about the rod. Any help?

    edit: it doesn't actually give you the mass of the rod in the question
     
    Last edited: Nov 29, 2010
  7. Nov 30, 2010 #6
    Re: a rod attached to a wall by a hinge, the rod is also attacked to a cord and a pul

    Any help please? Would be greatly appreciated!!
     
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