6.7C Key Concepts

Newton's Third Law of Motion

Overview

• Newton's Third Law states that for every action, there is an ____________ and ______________reaction.

• This law can be summarized as: When two objects interact, they exert forces on each other that are equal in __________ and opposite in _____________.

Historical Context

• Sir Isaac Newton, a seventeenth-century English mathematician and __________________, first proposed the three laws of motion, which are fundamental to classical mechanics.

Simultaneous Force Pairs

Definition

• A simultaneous force pair consists of ___________forces acting on two interacting objects at the ____________ time.

• Characteristics of simultaneous force pairs:

  • Equal in size

  • Opposite in direction

Magnitude of Forces

Understanding Magnitude

• The term “equal in size” pertains to the magnitude of the forces involved.

• Magnitude is defined as:

  • The size, quantity, or intensity of an object, action, or event.

Examples of Newton's Third Law

Example #1: Swimmer and Wall

• Scenario: A swimmer pushes against a wall.

  • The swimmer exerts a force on the wall.

  • Simultaneously, ________________________________________________________________.

Example #2: Paddle and Water

• Scenario: A paddle pushes against water.

  • The paddle exerts a force on the water in one direction.

  • In response, __________________________________________________________________.

Example #3: Rocket and Air

• Scenario: A rocket in motion.

  • The rocket exhausts gases, pushing air downwards.

  • The air, in turn, ___________________________________________________________.