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Homework Help: Replace all the loads on the beam with one resultant force.

  1. Aug 31, 2013 #1
    1. The problem statement, all variables and given/known data

    Knowing the distance d=1.5m, determine the resultant of the loads acting on the beam shown in the attachment. Specify the point of application of this resultant on the beam.

    Given data: F1=100KN, l1=1m. F2=50kN,l2=1.5m. F3=60KN, l3=4m.
    Variables: Resultant Force R, and its lever arm L.

    2. Relevant equations

    R=F1+F2-F3=90KN(Pointing downwards)
    Take the most left point as reference:
    M=-F1*l1-F2*l2+F3*l3=65 KN*m (Counterclockwise direction)

    3. The attempt at a solution
    The problem I have is that, since R is pointing downwards, it will never create a counterclockwise direction moment, hence this problem cannot be solved. But on my book, anwser is given like this:
    R=90KN downwards @0.722m from the left end

    Thank you for helping me:)

    Attached Files:

    Last edited: Aug 31, 2013
  2. jcsd
  3. Aug 31, 2013 #2


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    You have the 50 kN load located at 4m from the left end. This location does not match the attached diagram.
  4. Aug 31, 2013 #3
    Sorry for my mistake, corrected just now
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