Force polygon — where it appears
Named by 2 essays across one field — each of them below, with the objects they name alongside it.
Three forces must meet at a point, and a drawing can find it
A body held by exactly three forces has their lines of action concurrent. That is a theorem, it is enough to solve for direction and magnitude, and for a century it was done with a straightedge.
The angle that doubles the force
A crane hook takes the weight and nothing else. What holds the load is a set of legs running down to it at an angle, and each leg is a two-force member — so at thirty degrees from the horizontal each of two legs carries the entire load, and the difference goes into the thing being lifted as compression.
Named alongside it
The objects these essays reach for when they reach for this one.
Graphic staticsBucklingCentre of gravityConcurrencyEquilibriumErectionFree bodyFree body diagramFunicularIndeterminacyLine of actionLoad path