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## Homework Statement

http://img512.imageshack.us/img512/2617/staticsquestion4.jpg [Broken]

## Homework Equations

- Ability to resolve forces into components

- M = Fd

## The Attempt at a Solution

(a)

Resolve the force acting at an angle into components...

10kN force = -10cos50

**i**- 10 sin 50

**j**kN

Therefore, resultant R becomes...

= (-10cos50)

**i**+ (15 - 3 - 10 sin 50)

**j**kN

= -6.428

**i**+ 4.3396

**j**kN

(with a magnitude of 7.756kN)

(b) This is where I get stuck.

I basically calculated the moments created by the individual elements of R,

F1 = 15kn force

F2 = 3kn force

F3 = vertical component 10kn force

and, because I am using the joint with the wall as an origin, the line of action of the horizontal component passes through my origin thus no moment.

M1 = 15*3 = 45kNm

M2 = -3*1.5 = -4.5kNm

M3 = (-10 sin 50)*9 = -68.944kNm

Sum of moments = 45 - 4.5 - 68.944 = -28.444kNm

and then I get stuck. Do you add the moment you've just found to the moment provide in the couple, then sub. back into M=Fd where F=R?

Help!

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