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# Sir Isaac Newton: Three Laws of Motion

show/hide words to know

• Law: a well established idea in science and one that can be used in many ways.
• Mass: is used to describe how much matter is in an object. If you know the number of atoms, the density of the atoms, and what type of atoms are in an object you can calculate its mass.

## Newton's Three Laws of Motion

Here you will find the precise technical term for each of Newton's Laws of Motion. You will also find the easier to understand version of these laws.

1. Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.

What was that? Look at it this way.

Things only change motion if there is a force acting on them. Such as pushing or pulling.

2. The acceleration of a body is directly proportional to the net force acting on the body and inversely proportional to the mass of the body and is in the direction of the net force.

What? Think of it this way.

The amount of change in motion is less for big things than for small things. The second law says it is easier to push the empty cardboard box your refrigerator came in than the refrigerator.

3. Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first.

In other words... You cannot push on an object without that object pushing on you.

Sometimes this law is explained as "to every action there is always an opposed equal reaction."

## Stories

Besides his well known work on gravity, Newton also added to our knowledge of mathematics and physics.

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# Learn More

Besides his well known work on gravity, Newton also added to our knowledge of mathematics and physics.

Share to Google Classroom

## Be part of Ask A Biologist

by volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteer page to get the process started.