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Homework Help: Moment problem

  1. Feb 6, 2007 #1
    moment problem plz help

    1. The problem statement, all variables and given/known data

    a small boat hangs from two davits one of which is shown in the figure. the tension in line ABAD is 369 N. Determine the moent about C of the resultant force Ra exerted on the davit at A

    2. Relevant equations



    3. The attempt at a solution
    ok so first i took the 369N and multiplyed it by the unit vector
    (2.4i-3.1j-1.2k)/(2.4^+3.1^2+1.2^2)^.5 and got (216,-279,-108)
    ok then i took the cross product of (216,-279,-108) and (-2.4,0,0)when i did this i got (0,-259.2,670)but the i component shouldnt be zero please help
     

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    Last edited: Feb 6, 2007
  2. jcsd
  3. Feb 7, 2007 #2

    Tom Mattson

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    That distance of 3.1 meters doesn't look like it's parallel to the y-axis, but you're treating it as though it is parallel to it. Is it supposed to be vertical?
     
  4. Feb 8, 2007 #3

    AlephZero

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    Also, if "line ABAD" means the rope is double between A and B (as in your figure) there are three forces of 369N at point A, not one.
     
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