# Homework Help: Find the moment caused by all the forces

1. Feb 11, 2010

### 385sk117

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

two couples are acting on the frame. If the resultant couple is to be zero, find the distance d

2. Relevant equations

3. The attempt at a solution
First find the point, Let's say A on the picture, and find the moment caused by all the forces
500cos30 x 0.9 acting downward, 500cos30 x (0.9+d) acting upward, moments by 750ns are cancelled, at least that was what i thinking but i dont think this is right method to use..
is moment by couple = f.d ?
so d = 1.8m?
i dont get this........
Please help me TT

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2. Feb 11, 2010

### tiny-tim

Hi 385sk117!
No, you don't need to choose a point …

the moment of a couple is the same about any point.

So just use your f.d formula for each couple separately.

3. Feb 11, 2010

### 385sk117

Re: couple

Thankyou :)

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