Engineering Mechanics: Notation question

[CivilSigma]

In a problem involving moments where we have a 2 point is space: m and n.
We want the moment about M due to a force applied at N.
We know the equation is Moment = r (m/n) * F

So, does r (m/n) represent the (x,y,z) coordinates from the point N to M or M to N?

 

[GibsX]

The direction has to be perpendicular to the applied force. So, if the force is applied along the y axis, the direction should be in x axis. Hope that helps.

 

[OldEngr63]

The calculation of a moment is usually done in vector (cross product) form,
M = required moment (a vector)
= r_n/m x F

Note that, in the subscript on r, the first item is the point where F is applied while the second is the reference point for the moment.