Newton's first law of motion

Definition

Newton's first law of motion, also known as the law of inertia, states that an object at rest will stay at rest and an object in motion will stay in motion with a constant velocity unless acted upon by an external force.

Related terms

Inertia:

The tendency of an object to resist changes in its state of motion.

Force: A push or pull that can cause an object to accelerate.

Equilibrium:

When all forces acting on an object are balanced, resulting in no change in its state of motion.