Solve Force F Moment Problem: Find Mag. & X-Intercept

[asteg123]

The force F has a moment equal to 250N.m with respect to point O -400N.m with respect to point B and has a zero moment with respect to point A.

http://freewebs.com/mcroldan08/prob.jpg

Find the magnitude of F and the x-intercept.


OK, here's what I did,

Using the formula for moment I got the force F*sub*B

M=Fd
-400N.m=F(2.4m)
F=-166.67 N

I think this is the y-component... right??

anyways, I got F*sub*A as zero...

Now, I can't figure out a way to utilize the moment in O and as well as get the intercept and the force...

can anyone help me??

 

[OlderDan]

The line of the force must go through A to have no moment. Where does it have to be in relation to O and B so that the moments about those points have opposite signs?