Moment problem

  • #1
bobbarkernar
48
0
moment problem please help

Homework Statement



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

Homework Equations





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 shouldn't be zero please help
 

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Answers and Replies

  • #2
quantumdude
Staff Emeritus
Science Advisor
Gold Member
5,575
23
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?
 
  • #3
AlephZero
Science Advisor
Homework Helper
7,025
297
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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