Concept
Boundary — where it appears
2 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
The free body is a choice, and choosing it well is the whole skill
Cutting a structure open is not a step in the method. It is the method — and where the cut is made decides whether the answer takes one line or twenty.
The surface that carries by being curved
A flat plate spends its thickness on a lever arm of a few millimetres. Curve the same sheet and the load is carried in the surface itself, at a thirtieth of the thickness — and the entire bill is presented at the edges.
Named alongside it
The objects these essays reach for when they reach for this one.
CompatibilityEquilibriumFree body diagramFunicularHoop forceHorizontal thrustInternal forcesMembrane actionMethod of sectionsNewton's third lawReactionsSelf weight