I'm trying to understand couples, moments and forces. I know that a moment is a force causing a rotation about a certain point/axis. And I know a couple is a vector that represents the... and then that's where I'm trying to get clarification. Is a couple vector a representation of the general tendency of the entire rigid body to rotate as a result of two forces that qualify, and hence why the couple vector can be moved anywhere in space without affecting its value.? And in calculating moments about a certain point the couple is added up just like a regular moment at that point? Also if let's say a system is acted on by a couple vector and 3 forces. If you calculate the moment about a certain point, you add that couple vector with the moments of the other 3 forces? But when calculating a resultant force of just the 3 forces given, the resultant force should cause the same moment about that point as the moment with the couple included?