Newton’s 3rd Law

What is physics?

astronomer

Law of Universal Gravitation

1643-1727 calculus

Laws of

Motion

physicist

mathematician

Who is Newton?

Isaac Newton Bio

In this lesson, we will be focusing on Newton’s 3rd Law of Motion3rd Law of Motion.

This law is all about pairs of forces called…

action and reaction forcesaction and reaction forces

Let’s learn a little about these forces…

ESA –stop at summary of 3 laws

Newton’s 3rd law in Space

To recognize Newton’s 3rd Law of Motion3rd Law of Motion

look for pairs of forces…

““action” action” is the force that happens first,

causing a “reaction” “reaction” force to happen

These equal forces happen in opposite directions.

Newton’s 3rd Law

Key Idea is action-reactionaction-reaction

The Law says…

for every actionaction (force) there is an equalequal and oppositeopposite

reactionreaction (force)

Let’s look at some examples.

When you sit in a chair… (action forceaction force)

the chair must be pushing back…(reaction forcereaction force)

these forces are equal in strength and opposite in direction, otherwise you’d land on the floor!

Reactio

n

At Rest…

When you lean against a wall…(action forceaction force)

the wall must be pushing back equally hard…

(reaction forcereaction force)

otherwise you’d go through the wall!

At Rest…

Actio

n

For moving things…

an action force action force in one direction creates an equal and opposite

reaction force reaction force in the opposite direction

an action force action force in one direction creates an equal reaction force reaction force

in the opposite direction

FMA_Live

FMA Live – Action/Reaction

If you haven’t already figured it out…

the key idea of Newton’s 3rd Law isAction – ReactionAction – Reaction

The Law says…

For every action (force)action (force), there is an equal and opposite reaction (force)reaction (force)

Now, it’s your turn to see if you can identify

Newton’s 3rd Law in these demonstrations…

Look for equal action – reaction force action – reaction force pairs

going in opposite directions

RifleRecoil

Rifle Recoil

Cannon

Cannon

Shuttle Launch

Shuttle Launch

Newton_Sled

Newton’s Sled

iPod_Cradle

Newton’s Cradle

Dominoes

Dominoes

Space Tools

Space Tools

Extras....More videos showing

Newton’s 3rd Law

Dr Carlson

Dr. Carlson’s Science Theater

Equal_Mass

Equal Mass

Unequal_Mass

Unequal Mass

Balloon Cars

Balloon Cars