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Homework Help: Torque Equilibrium and Elasticity problem

  1. Feb 15, 2012 #1
    1. The problem statement, all variables and given/known data
    A 300 kg nonuniform boom, 6.0 m long, is loosely pinned at the pivot at P. A 1000 kg
    block is suspended from the end of the boom at A. The boom forms a 30° angle with
    the horizontal, and is supported by a cable, 4.0 m long, between points D and B. Point
    B is 4.0 m from P, and point D is 4.0 m above P. The center of mass of the boom is at
    point C, which is 2.0 m from P. Find the tension in the cable, and the x- and
    y-components of the force of the pivot on the boom.

    http://img202.imageshack.us/img202/262/50669209.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution

    I calculated torques clockwise and counterclockwise and set them equal to each other, which are perpendicular so using the weight I solved for the Force perpindicular

    (Fw(rod)*cos(30)*2)+(Fw(block)*cos(30)*6) = Ftcos(30)*4,

    this gives me the Force of tension in the rope, from which i use to split into its X and Y components, and then I get the incorrect answer.

    any help would be appreciated, thanks in advance
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Feb 15, 2012 #2


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    Homework Helper

    Hi Elysian,
    You get the force of friction from your equation.
    The next question is the x and y components of the force of the pivot. That force is not the same as the tension. Show your work in detail.

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