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Homework Help: Two Ladders Hinged at Point A

  1. Jun 18, 2014 #1
    1. The problem statement, all variables and given/known data
    Two ladders, 4.00 m and 3.00 m long, are hinged at point A and tied together by a horizontal rope 0.90 m above the floor. The ladders weight 480 N and 360 N respectively, and the center of gravity of each is at its center. Assume that the floor is freshly waxed and frictionless.
    • a) Find the upward force at the bottom of each ladder.
    • b) Find the tension in the rope.
    • c) Find the magnitude of the force one ladder exerts on the other at point A.
    • d) If an 800 N painter stands at point A, find the tension in the horizontal rope.

    Image: http://www.solutioninn.com/images/P-M-EE%20(98).PNG
    2. Relevant equations

    3. The attempt at a solution
    For part a I attempted to do net torque, but I cannot figure how to account for all of them. The book says that the answer for part a is 391 for the left ladder (4m one) and 449 for the right ladder (3m one).
  2. jcsd
  3. Jun 18, 2014 #2


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    Gold Member

    How many do you think there are? Perhaps start by adding forces and dimensions to the diagram and posting that so we can see where you are going wrong. eg Which ones can't you account for?

    Hint: I have an origin and three forces on my version.

    I get the book answer.
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