This 3D model needs a browser with WebGL turned on. The explanation for each stage still works: use the stage buttons below.
Spanner on a nut
moment = force × perpendicular distance from the pivot
Distance not used: pushing along the spanner, the line of action goes through the pivot wherever you push.
Metre rule on a pivot
total clockwise moment = total anticlockwise moment
Distances and moments are for the rule held level. An unbalanced rule is drawn tipped, but the distances shown are still measured along the level rule.
Tilt it, then let go
line of action inside the base outside the base