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Help with pulley problem with sag

  1. Sep 18, 2009 #1
    1. The problem statement, all variables and given/known data

    F3-3.jpg

    If the 1.5 kg block is suspended from the pulley B and the sag of the cord is d = 0.15m, determine the force in cord ABC. Neglect the size of the pulley


    3. The attempt at a solution

    They dont even give an angle, im not sure how im supposed to do this.
     
  2. jcsd
  3. Sep 18, 2009 #2

    rl.bhat

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    Homework Helper

    Draw a perpendicular from BD on AC. That bisects AC.
    In triage BDC you can all the three sides.So fond the angles.
     
  4. Sep 18, 2009 #3
    so for the angle i got 53.3 degrees. Tan^-1(0.2/0.15) = 53.3 degrees

    Then i made components

    Force x y
    AB -ABsin53.3 ABcos53.3
    CB CBsin53.3 CBcos53.3
    14.715N 0 -14.715


    X axis = 0 N

    CBsin53.3 - ABsin53.3= 0

    y axis = 17.715 N

    CBcos53.3 + ABcos53.3 = 14.715 N


    so then i substituted for CB = ([14.715 / cos53.3] - AB)
    = 24.62

    and got 12.3 as the tension total. thankyou
    i was confused by how the lines in the diagram are different sizes and did not think that the pulley would be in the center with a diagram like that
     
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