Replace with equivalent force-couple system?

[SUCRALOSE]

Replace with equivalent force-couple system??

My book has one page on this and I do not understand what they want...

Please see attached picture for problems..

First one, left side, says replace the 5KN force with an equivalent force-couple system at O.

and

The second one says to replace the 500N force with a equivalent force-couple system at B.

Thanks a lot

 

[Spinnor]

I think what you want is C = rXF where r is the vector from the point in interest to the point where the force acts and F is the applied force vector.

C = r_x*F_y - r_y*F_x

See, "What is a couple?"

In

http://plus.maths.org/content/unspinning-boomerang