1. Gravity and Inertia

2. Gravity
The force that pulls objects towards each other – a force of attraction between objects!
On Earth, gravity is pulling everything straight down toward the center of the Earth (of course we get stopped by the ground)

3. Weight
Weight is the force of gravity on a person or object on the surface of a planet
Weight depends on mass and the force of gravity at a specific location

4. Mass
The measurement of the amount of matter “stuff” in an object

5. Inertia The tendency of an object to resist a change in its motion
Mass changes an object’s inertia – the more mass the more inertia… the object will be harder to start or stop

6. Force
A push or a pull between objects

7. The Universal Law of Gravitation
The force of gravity acts between all objects in the universe.
This means that all objects attract each other!

8. Factors Affecting Gravity
Mass – the greater the mass the greater the gravitational force
Distance – the smaller the distance, the greater the gravitational force

9. with the same amount of force!
The Earth and you
You are attracted to the Earth and the Earth is attracted to you
You pull on the Earth and the Earth pulls on you…
with the same amount of force!

10. Falling
Why when we fall are we pulled down towards the Earth instead of pulling the Earth up towards us?
The Earth has a whole lot more mass (more inertia) – needs more force to move!

11. Why are we pulled more towards the Earth than the moon?
The Earth has more mass and is closer to us!

12. Mass and Weight on the Moon
Your mass will not change on the moon
Your weight will decrease since there is less gravity on the moon
There is less gravity on the moon because the moon is less massive than the Earth

13. Weight on other planets
Gravity on the other planets depends on the mass of the planet and the radius of the planet