Definition

1. Noun:
   • Newton's third law of motion: A fundamental principle of classical mechanics formulated by Sir Isaac Newton. It states that for every action, there is an equal and opposite reaction. This means that 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

• Noun: The term is used as a singular, proper noun phrase to describe this specific physical law. It is often cited in physics to explain interactions between two bodies.
  • The principle is formally known as Newton's third law of motion.
  • To understand how rockets work, you must apply Newton's third law of motion.

Examples

• Noun:
  • When you push against a wall, the wall pushes back on you with an equal force; this is a demonstration of Newton's third law of motion.
  • The textbook chapter explains Newton's third law of motion in detail with several practical examples.
  • A common paraphrase of Newton's third law of motion is: "To every action there is always opposed an equal reaction."

Advanced Usage

• "To obey/violate Newton's third law of motion": Used to describe whether a system or a described interaction is consistent with this fundamental law.
  • Any conceivable propulsion system must obey Newton's third law of motion.
• The law is often a foundational concept in analyzing force pairs or action-reaction pairs.

Variants and Related Words

• Third law of motion: A common shortened form.
• Law of action and reaction: A descriptive synonym.
• Newton's third law: The most frequent abbreviated form in technical and casual discourse.
• Action-reaction principle: A descriptive phrase explaining the law's core idea.

Synonyms

• Law of action and reaction: A direct synonym describing the equal and opposite forces.
• Action-reaction law: Another descriptive synonym.

Related Phrases

• Action-reaction pair: Refers to the two forces described by the law.
  • Identify the action-reaction pair when a hammer hits a nail.
• Equal and opposite: A key phrase from the law's common statement.
  • The forces are equal and opposite, as per Newton's third law.

Noun

1. action and reaction are equal and opposite