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Homework Help: Equillibrium: torque and net force

  1. Mar 3, 2015 #1
    1. The problem statement, all variables and given/known data
    http://imgur.com/rWsNsmp [Broken]

    2. Relevant equations
    net torque = 0
    net force = 0
    3. The attempt at a solution
    Finding f1 was easy.
    f1 = wladder + person = 885.92 N
    Then the horizontal forces are also equal:
    f2 = f3

    Now net torque = 0 (I'm using moment arm because there is no angle given):
    f3(3.8) = wladder(moment arm) + wperson(0.70)

    I can't manage to figure out the moment arm. I'm not sure if 0.7 meters can be used because I think that is the moment arm for the force of the person only. No angles were given, all I know is that the distance from the bottom of the ladder to the center of mass of the ladder is 2 meters.
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Mar 3, 2015 #2


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    Science Advisor

    Oh, yes, they were (but indirectly). Length of ladder = 4m, vertical height of ladder = 3.8m.
  4. Mar 3, 2015 #3
    Didn't think about it that way. Thanks!
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