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Homework Help: Crane static problem

  1. Jul 17, 2008 #1
    crane static problem....

    1. The problem statement, all variables and given/known data
    A 25-ft. crane supported at its lower end by a pin is elevated by a horizontal cable. A 250 lb. load is suspended from the outer end of the crane. The center of gravity of the crane is 10 ft. from the pin, and the crane weighs 200 lbs. What is the Tension in the horizontal cable?

    2. Relevant equations

    t = I (alpha)
    F = ma
    Sums of F = 0
    Sums of t = 0
    r x F = t
    Magnitude of t = Fdsin(theta)

    3. The attempt at a solution

    I have no idea, I tried doing a basic way of doing the load force mechanics but i realized it's not only that there's something with torque and the load proportion I don't know about.

    Attached Files:

  2. jcsd
  3. Jul 17, 2008 #2


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    Science Advisor
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    Gold Member

    Re: crane static problem....

    For a system in equilibrium, there is no acceleration, so scratch out your first 2 relevant equations. Try summing torques about the lower pivot, and note also that the weight forces act through their center of mass, and that tension forces act along the longitudinal axis of the cable (horizontally in this case). You must show some work before we can be of further assistance.
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