Structural Engineering & Statics
where the load goes
Concept

Equilibrium — where it appears

2 essays name this object, across one field. What follows is each of them, and the objects they name alongside it.
2012.57.5shear 7.5moment 22.5the cut, at x = 5nothing was applied here — the internal forces are what the left-hand piece needs

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.

equilibrium · free body 15°reaction, leaning 15.0° from the normalthe cone: half-angle arctan μ = 19.3°W = 100demand 25.9 against a capacity of 33.8 — F/μN = 0.77the weight appears nowhere in the cone — only the direction of the reaction is asked about

The force that is whatever it needs to be

Every other force in statics has a value the equations produce. Friction has an inequality instead, so it takes whatever value equilibrium demands and the bound only ever says no — which means a problem with friction in it has a range of answers rather than one.

equilibrium · friction

Named alongside it

The objects these essays reach for when they reach for this one.

Angle of reposeBoundaryFree bodyFree body diagramFrictionIndeterminacyInternal forcesMethod of sectionsNewton's third lawOverturningReactionsSelf locking

All concepts