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Homework Help: This one is a doozy.

  1. Sep 14, 2005 #1
    I've been trying to find the answer for a good hour and a half now.

    It involves a 1200 N uniform boom that is supported by a cable perpendicular to the boom. The cable makes a 25 degree angle to the horizontal and hooks up at 3/4 of the entire length of the boom. The boom hinges and makes a 65 degree angle to the horizontal. There's a weight that hangs from the top of the boom that's 2500 N. I'll try to illustrate it a bit:

    | _
    |....._ ../|
    |......../ |
    |......./ []

    (at least as good an illustraton as my physics teacher can make)

    I need to find the tension of the cable that connects the boom to the wall and the horizontal and vertical components of the reaction force exerted on the boom by the hinge. I don't really need an answer, just an explanation of how to find them. Any help is greatly appreciated.
  2. jcsd
  3. Sep 14, 2005 #2
    Try setting up the problem with vectors. The sum must equal 0 for static equilibrium.
  4. Sep 14, 2005 #3
    I understand that I should use vectors and that net torque is 0...

    Unfortunately, I can't seem to apply it to this problem.
  5. Sep 14, 2005 #4
    I know the tension will a force that contributes to the torque, but I don't understand how to fin the displacement or find any other variables involved.
  6. Sep 15, 2005 #5
    If the net torque around a point is zero, then they are zero around all points. So, I think this would let you put the pivot at the hinge. Wouldn't that make the torque calculation simpler?

    The rest is just adding up the F_x forces and the F_y forces.

  7. Sep 15, 2005 #6
    Thanks, I'll try it.
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