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Homework Help: Statics Forces Problem (Trusses)

  1. Sep 29, 2012 #1
    1. The problem statement, all variables and given/known data

    I was doing a problem with my friend (the image that is attached to this) and when looking up a solution online... It said that the forces at reaction supports B and C are 5 kN in the y direction...

    2. Relevant equations

    3. The attempt at a solution

    We thought that since these members are trusses, all the force from the external loading... is 15 (10 + 5) and that the reaction supports in the y direction at B and C should be 7.5. Where did we go wrong?

    Thank you! :)

    Attached Files:

  2. jcsd
  3. Sep 29, 2012 #2


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    What is the reaction force at A ?
  4. Sep 29, 2012 #3
    If it is a truss... Do we still account for the reaction force at support A in the y direction?

    If this was the case and I took the moment at A I would get :

    -1*(10) + -2*(5) + (2-0.707)*By + (2+0.707)Cy = 0
    => 1.293*By + 2.707*Cy = 20

    And for the sum in the y direction of the system:

    Ay + By + Cy = 15

    (Assumption) Since Cy = By:

    By = 5
    Cy = 5
    Ay = 5
    ... Ok... I just solved it... :P

    Thanks Dude. :D
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