The question is…

Why does everything in the universe move?

why?

The answer…

Big, huge, massive forces!

And little ones too.

Forces PG 39 A force is a pull (an attraction)

Or, a push (a repulsion)

Forces PG 39 1. All forces have two properties:

a)Direction b)Size

2. A newton (N) is the unit that describes the size of a force and is equal to 1kg X m/s2

Newton’s Laws of Motion •Newton lived from 1642–1727• Law #1 An object in motion stays in

motion and an object at rest stays at rest unless acted upon by an unbalanced force• Law #2 Force equals mass times

acceleration (F = ma)• Law #3 For every action there is an equal

and opposite reaction.

• BrainPoP- Newton’s Laws of Motion

Newton’s First Law

An object in motion stays in motion and an object at rest stays at rest unless

acted upon by an unbalanced force

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Observe the Effects of Inertia (Mini Lab Demo)Page 38 (notebook)

•Procedures and Materials:•Data and Observations:•Analysis:

1. Identify the forces acting on the object in the cart in both runs.

2. Explain why it is important to wear safety belts in a car.

1. Identify the forces acting on the object in the cart in both runs.

Newton’s First Law

•What does this mean?•An object will keep doing what it’s doing UNLESS acted on by an unbalanced force like friction• If it is moving at a constant

velocity it will continue • If it is at rest, it stays at rest

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Newton’s First Law with Seat Belts

Don’t let this be you

Due to inertia, objects (including you) resist changes in their motion. When you and the car going 80 km/hour is stopped by the brick wall, your body keeps moving at 80 km/hour

•An object with a net force of anything other than 0 N on it will change its state of motion.

Net Force (Resultant Force)

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Forces in the Same Direction

•When forces are applied in the same direction, they are added to determine the size of the net force

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•When two forces act in opposite directions, you subtract the smaller force from the larger force to determine the net force • The net force will be in the same direction as the larger force

Forces in Different Directions

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Balanced forces cancel each other out!They are forces that are equal in size and opposite in direction

Balanced Forces

IS THERE MOTION? OR FORCE? EXTERNAL FORCES ACTING UPON THEM?

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