The moments are real for each example given.
The causative forces vary, depending on from which point you want to measure them.
For example, you can close a door in 3 seconds either by using a small force near the handle or a large force near the hinge. The moment (N x m) will be the same in both cases.
However; given that you can chose any point about which the moments may be analysed, and given actual forces of weight, lift, drag, etc. the whole exercise is somewhat arbitrary. It's a bit like the notion of 'centre of gravity'; an arbitrary point at which the mass of a body can be said to act (which may even lie outside the body in question).
Last edited by eckhard; 10th Dec 2016 at 12:27.