Finding moments about a point in static equilibrium

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Homework Statement


See attached file


Homework Equations


[tex]M_A = Fd[/tex]


The Attempt at a Solution


I using the above equation..just summing all of the forces and their directions but I keep getting the wrong answer(distances from the moment). I also tried summing all the forces from point G (Center of gravity). This gave me a close answer but not exact. How should I go about doing this?
 
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  • Hand-drawn free-body diagram of an aerial work platform boom at 30 degrees, with a 4000N load at the centre of gravity G, a 5 m boom length, a 4 m and 0.5 m distance labelled, a moment M at pivot A, and a weight W at the platform base.
    boom3.jpg
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you said your answer is close to the answer given right?well i was wondering maybe you left out the 0.5m in the claculation?
 
Does the force acting through the Center of gravity come into play?
 
suspenc3 said:
Does the force acting through the Center of gravity come into play?
Yes. It is easiest to sum moments about the right end, and set them equal to 0. If you sum moments about G, you still need to know the force through G in order to calculate the reaction force at the right end, which will then contribute to the moment about G. When you sum moments about the right end, you don't need to know that force to do so, since it doesn't contribute to the torque.