# Chapter 4: Newton's Three Laws

Difficulty Level:

**At Grade**Created by: CK-12

Newton's three Laws of Motion are the core of our understanding of *force*, which is how objects affect each others' motion. In this chapter, we will cover the definition of force, an object's innate resistance to being moved by force - called *inertia*, and how forces interact with each other.

## Chapter Outline

### Chapter Summary

**Newton’s Three Laws**

- Newton’s First Law of Motion: An object remains at rest or in a state of uniform motion unless acted upon by an unbalanced force.
- Newton’s Second Law of Motion: The acceleration,
a , that an object experiences is directly proportional to the net force acting on the object,∑F or(Fnet) , upon it and inversely proportional to its mass,m .∑F=Fnet=Ma - Newton’s Third Law of Motion: Whenever two objects interact they must necessarily place equal and opposite forces upon each other.
Fab=−Fba

**Solving problems using Newton’s Laws**

Steps

- Read the problem carefully and draw a rough sketch of what is happening
- Draw a careful Free-Body-Diagram for each object in the problem.
- Write an equation associated with each Free-Body-Diagram using Newton’s Second Law.
- Add other equations if necessary.
- Solve the system of simultaneous equations.
- Check your results to see if they are physically reasonable.

### Image Attributions

## Description

Covers inertia, force, how force causes acceleration, and how objects causes force against each other.

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## Date Created:

Jun 27, 2013## Last Modified:

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