Determine the value of the couple

1. Jul 30, 2009

piacere_space

Consider the drawing of the lever. Determine the value of the couple, M, so that the resultant of the applied loads passes through the point O. The applied loads include the two forces (400 N, and 320 N), and the couple M.

M=400$$\times$$0.15$$\times$$cos30+320$$\times$$0.3=148(Nm)

Is this equation wrong?
I just didn't get what this question is actually asking...

2. Jul 30, 2009

djeitnstine

Re: Couple

A diagram would be helpful but from what I can gather, you know that any moment created by a force is is F*d, force times distance. But the summation of these is the total moment. So you need to replace the forces by one single couple moment.

So you get an equation that looks like $$\sum M_O = \pm F_1 d \pm F_2 d$$ where $$\sum M_O = M$$ (resultant) and d is the moment arm. I placed plus/minus there depending on the direction of the applied forces.

I do not know anything of what the problem looks like but the concept behind your equation is correct.