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How do I know which direction the horizontal force acts

  1. Apr 30, 2015 #1
    1. The problem statement, all variables and given/known data
    I am to find the reactions of a 3 pin frame.

    2. Relevant equations


    3. The attempt at a solution
    So how do I know which direction to label the horizontal reactions? In the diagram HA and HF are in the same direction, I was under the impression that reactions are opposite to applied force. Photo 30-04-2015 21 44 56.jpg

    I have no problems calculating a solution once i know which direction the reaction occurs.
     
  2. jcsd
  3. Apr 30, 2015 #2

    SteamKing

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    Staff Emeritus
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    Homework Helper

    Uhh, looks like someone has drawn in the direction of the horizontal forces at pins A and F.

    This is why PF Rules request that posters provide a complete description of the HW problem and use of the HW template.
     
  4. Apr 30, 2015 #3
    Yes that was me. I know the method to calculate a solution providing I know which directions the horizontal reaction forces act.

    My question was how do I know which direction the reaction forces act or what bit of information in that diagram tells me that HA and HF both act to the Right.
     
  5. May 1, 2015 #4

    donpacino

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    Gold Member

    If you draw the forces in the wrong direction, you will simply get a negative number in your answer!
     
  6. May 1, 2015 #5
    I have already solved my problem and would have marked it solved if i knew how. Your answer was the one I was looking for, thank you for taking the time to read the problem and reply.
     
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