## First Condition of Equilibrium

An object that is motionless or undergoes no translational and rotational acceleration is said to be in equilibrium. That is, the net force and net torque on the object is zero in all directions. For an object to truly be in equilibrium, two conditions must be met.

The first condition states that the net force acting on the object must be zero. This means that for each axis of motion, the forces acting along that particular axis must sum to zero.

Expressed as an equation, this is simply:

Note that if net *any* direction is zero.
For example, the net external forces along the typical *x*- and *y*-axes are zero.
This is written as

and illustrate situations where

But remember, for true equilibrium, condition 1 is only half the picture.