law of action and reaction

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law of action and reaction

A student demonstrates the law of action and reaction with two toy cars on a table.

Definition

Noun: * Newton's third law of motion: The principle in physics stating that for every action (force) there is an equal and opposite reaction (force). When one object exerts a force on a second object, the second object simultaneously exerts a force equal in magnitude and opposite in direction on the first object.

Usage

This term is used almost exclusively in scientific contexts, particularly in physics and engineering, to describe a fundamental law of motion. * It explains the mechanics behind propulsion, collisions, and many everyday phenomena. * It is often cited in its full form, Newton's third law of motion, or simply as the third law.

Examples
  • The law of action and reaction explains how a rocket propels itself forward by expelling exhaust gases backward.
  • When you push against a wall, the wall pushes back on you with an equal force; this is a demonstration of the law of action and reaction.
  • According to the law of action and reaction, the force a swimmer applies to the water is matched by the force the water applies to propel the swimmer forward.
Advanced Usage
  • Conceptual Application: The principle is sometimes referenced metaphorically outside of physics to suggest that events or decisions can have direct and opposite consequences.
    • In geopolitics, some analysts describe sanctions as an action that often produces a reaction in the form of counter-sanctions.
Variants and Related Words
  • Newton's third law (of motion): The most common and precise synonym.
  • Third law: A common abbreviated form used in technical discussions.
  • Action-reaction principle: A descriptive alternative name.
Synonyms
  • Newton's third law
  • Action-reaction principle
Related Idioms or Phrases
  • For every action, there is an equal and opposite reaction: This is the colloquial, proverbial phrasing of the law, often used even in non-scientific contexts to imply inevitable consequences.
    • He spread rumors about his colleague, but for every action, there is an equal and opposite reactionsoon, people began to question his own credibility.
law of action and reaction

A student demonstrates the law of action and reaction with two toy cars on a table.

Noun
  1. action and reaction are equal and opposite