Equilibrium (AQA A-Level Further Maths): Quizzes

No net motion from forces and couples

All forces lie in the same plane

Zero resultant force and zero total moment

Three equations

Perpendicular to surface, no friction

To eliminate them from moment equation

$\sum F_x = 0$, $\sum F_y = 0$, $\sum M = 0$

$\mathbf{M} = \mathbf{r} \times \mathbf{F}$

Resultant force zero, total moment non-zero

Horizontal and vertical (perpendicular)