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Three Laws of Motion

Definition

The Three Laws of Motion, formulated by Sir Isaac Newton, describe how objects move. They include the law of inertia (an object at rest stays at rest and an object in motion stays in motion unless acted upon by a force), the law of acceleration (force equals mass times acceleration), and the law of action-reaction (for every action, there is an equal and opposite reaction).

Analogy

Think about playing pool. When you hit a stationary ball with the cue ball (law of inertia), it moves depending on how hard you hit it (law of acceleration) and when it hits another ball, that ball moves while the first one stops or changes direction (law of action-reaction).

Related terms

Newton's First Law: This is also known as the law of inertia which states that an object will remain at rest or move in a straight line at constant speed unless acted upon by an external force.

Newton's Second Law: This law states that the rate of change in momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts.

Newton's Third Law: Also known as action-reaction principle, this law states that for every action there is an equal and opposite reaction.