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Homework Help: Statics Homework problem - Reactions of Ball and Socket

  1. Oct 18, 2009 #1
    1. The problem statement, all variables and given/known data
    The pipe assembly shown in the picture supports the vertical loads shown. Determine the reactions at the ball and socket joint (point A) and the tension in the two cords BC and BD.


    2. Relevant equations
    Sum of Forces = 0
    Sum of Moments = 0

    3. The attempt at a solution
    I first caluclated the unit vector for the BC and BD connections and then I drew a free body diagram at point B. I've attempted many differ way to go about this, but none of them seem right. I came up with the Tensions BC and BD being equal (and opposite) to 12.6 kN though that's probably not right.

    I'm not sure about the reactions at point A, because I thought that any moment around a ball and socket is zero?

    I've been stuck on this for days and it's due tomorrow at 3!

    Please help me,
    Thanks so much
  2. jcsd
  3. Oct 18, 2009 #2


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    Homework Helper

    The ball and socket joint can only push in the AB direction. My instinct is telling me that A is the point the moments should be taken from. Certainly the sum of the moments there is zero or it would turn. Anyway doing it that way would be an excellent check on your work.
    Curious, I see in the diagram that BC and BD are in the horizontal plane but the diagram dimensions indicate B is only half as high as C and D.
  4. Oct 19, 2009 #3
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