The body is said to be in equilibrium if the resultant of all forces acting on it is zero. There are two major types of static equilibrium, namely, translational equilibrium and rotational equilibrium.

**Formulas**

Concurrent force system

$\Sigma F_x = 0$

$\Sigma F_y = 0$

Parallel Force System

$\Sigma F = 0$

$\Sigma M_O = 0$

Non-Concurrent Non-Parallel Force System

$\Sigma F_x = 0$

$\Sigma F_y = 0$

$\Sigma M_O = 0$