Mrs. Wright

NEWTON’s FIRST LAW of MOTION

FORCE

A force is a push or a pull on an object.

All forces have a STRENGTH (measured in NEWTONS) and a direction.

For Example: It takes about 45N

to lift the average cat

Sir Isaac Newton

In the late 1600’s Sir Isaac Newton developed 3 laws to describe how objects move and react in our universe to forces such as Gravity Friction Inertia

In order to understand these laws, you must first understand INERTIA.

INERTIA~ AKA: Law of inertiaInertia - the tendency of an object to resist being moved, or if the object is moving, to resist a change in speed or direction until an outside force acts on the object

ORThe tendency of an object to resist any changes in motion.

These pumpkins will not move unless acted on by an unbalanced force.

Newton’s 1st law of motion

An object at rest remains at rest, and an object in motion remains in motion at the constant speed and in a straight line unless acted on by an unbalanced force.

Objects At Rest:

An Object at rest is….

A.) not moving

B.) moving

Objects At Rest:

An Object at rest is….

A.) not movingB.) moving

Objects At Rest:

Objects at rest, such as a chair, desk, book, etc…, will not move by itself unless a force is placed on it.

AHHHH…GHOST!!!

At rest (not moving)

Unbalanced force (moving)

Objects In Motion

Moving objects will continue to move forever in the same velocity unless an unbalanced force acts on them.

QUESTION…

Scenario…You are riding a bus to school. When you finished your candy bar, you stand up to walk to the front of the bus.

SUDDENLY, a mouse runs in front of the bus and the bus driver slams on his brakes (he loves mice)…….

What will happen to you?why?

Friction & Newton’s First LawNewton says, “an

object in motion will stay in motion forever…unless acted on by a unbalanced force.

If you push your desk, what will happen?

Will the desk move FOREVER?

What makes it stop?

FRICTION!!!!!

Friction- a force that opposes motion between two surfaces that are in contact.

Mass & Inertia

The smaller the mass, the less the inertiaSmall/light objects are easier to move, or stop from moving.Large/heavy objects are harder to move, or stop from moving.

Wile E. Coyote

Watch CLIP and write down 3 examples of when Newton’s first law of motion was demonstrated. After the clip, go back and briefly explain WHY it demonstrates Newton’s 1st law.

VOCABULARY ~

Speed: The distance traveled by an object in a certain amount of time

Acceleration: The CHANGE in speed of an object

Law: A scientific theory that has been proven consistently true. Usually laws help explain how our universe works.