A-Level Physics – Newton’s Laws of Motion

Newton’s Three Laws of Motion are the foundation of classical mechanics. They are used to explain how and why objects move.

Newton’s First Law – an object remains stationary or moves at a constant velocity unless acted upon by a resultant external force.

Newton’s Second Law – force is equal to change in momentum over time. Often simplified to forces = mass x acceleration assuming the mass is constant.

Newton’s Third Law – every action has an equal but opposite reaction.

In this lesson we discuss the laws in detail and look at how they are applied in an exam question.