What Are Newton's Three Laws of Motion?

By Staff WriterLast Updated Apr 3, 2020 4:52:47 AM ET

Newton's First Law of Motion is the Law of Inertia, and the Second Law of Motion expresses the relationship between force, mass and acceleration. The Third Law of Motion states that "for every action, there is an equal and opposite reaction."


Newton's First Law of Motion, or the Law of Inertia, states that "every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." This means that there is a natural tendency for a moving object to keep moving, unless an external force interferes.

According to the Second Law of Motion, acceleration is produced when a force acts on a mass. The greater the mass, the greater the amount of force required. Force equals mass times acceleration.

The Third Law of Motion states that for every force, there is a reaction force that is equal in size, but opposite in direction. Therefore, whenever one object pushes another object, it gets pushed in the opposite direction equally as hard.