<h2>Summary</h2>
<ul>
<li><strong>Newton’s first law of motion</strong> states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force. This is also known as the <strong>law of inertia</strong>.</li>
<li><strong>Inertia</strong> is the tendency of an object to remain at rest or remain in motion. Inertia is related to an object’s mass.</li>
<li><strong>Mass</strong> is the quantity of matter in a substance.</li>
</ul>
<h2>Glossary</h2>
<h3>inertia</h3>
<p>the tendency of an object to remain at rest or remain in motion</p>
<h3>law of inertia</h3>
<p>see Newton’s first law of motion</p>
<h3>mass</h3>
<p>the quantity of matter in a substance; measured in kilograms</p>
<h3>Newton’s first law of motion</h3>
<p>a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force; also known as the law of inertia</p>
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Summary and Main Ideas

Physics is a science discipline concerned with the nature and properties of matter and energy. Physics topics include mechanics, heat, light and radiation, sound, electricity, magnetism, the structure of atoms, and so on.

Physics

Discover the development of the force concept, explore Newton&#8217;s first, second, and third laws of motion, and learn about problem-solving strategies and further applications in this tutorial on dynamics and the four basic forces.


Force and Newton's Laws of Motion

Development of Force Concept

Extended Topic: The Four Basic Forces—An Introduction

Further Applications of Newton’s Laws of Motion

Newton’s First Law of Motion: Inertia

Newton’s Second Law of Motion: Concept of a System

Newton’s Third Law of Motion: Symmetry in Forces

Normal; Tension; and Other Examples of Forces

Problem-Solving Strategies

Summary and Main Ideas

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