1. Gravitation

2. Why do things fall?

3. Objects will consciously return to where they belong
A bit of history
Aristotle
Believed that all things are made up of a combination of the four basic elements: Earth, Water, Air, Fire.
Objects will consciously return to where they belong

4. Newton
Described gravity as a force that exists between objects with mass.

5. Einstein Objects with mass cause space and time to bend around them.
Objects with more mass bend space more

6. How did Newton come to his conclusions?
Forget everything you know about gravity and put yourself in Newton’s shoes.
How did he come up with the relationships?

7. What is the connection between the two?
Questions?????
2. Why does the moon orbit the Earth?
What causes apples to fall?
What is the connection between the two?

8. Newton’s Cannon

9. What is the relationship between Mass and Gravity?

10. What is the relationship between Distance and Gravity?

11. What is the connection between Gravity and Mass?
We saw in the activity during class the other day that there is a relationship between objects with mass and the force of gravity.
What are the variables that affect the force of gravity between objects in the Solar System?
How are these variables related?
𝐹 𝐺 = 𝑀 𝑠𝑢𝑛 ∗ 𝑚 𝑝𝑙𝑎𝑛𝑒𝑡 𝑟 2 𝐺
Msun
mplanet
What is G?
The Universal Gravitation Constant: r
𝐺=6.67∗ 10 −11

12. Do things change if this is viewed on a small scale instead of planet size?
Noooooo!!! The equation still works the same even for small things here on the Earth m1 m2 r
𝐹 𝐺 = 𝑚 1 ∗ 𝑚 2 𝑟 2 𝐺
𝐺=6.67∗ 10 −11

13. So why don’t things float together here on the Earth?
How much gravitational force is there between Big Mouth and his Donut?
1.5m
𝐹 𝐺 = 𝑚 1 ∗ 𝑚 2 𝑟 2 𝐺
m = 0.5 kg
𝐹 𝐺 = 85∗ 𝐺
m = 85 kg
𝐹 𝐺 =18.89∗(6.67∗ 10 −11 )
𝐹 𝐺 =18.89∗𝐺
𝐹 𝐺 =1.26∗ 10 −9 𝑁

14. Relationships between variables:
What would happen to the amount of force if you doubled one of the masses?
x 2
What would happen to the amount of force if you tripled one of the masses?
x 3
What would happen to the amount of force if you doubled one mass and tripled the other?
x 6
What would happen to the amount of force if you cut the distance in half?
x 4
What would happen to the amount of force if you tripled the distance?
x 1/9

15. What type of force is Gravity?
ATTRACTIVE!!!!!!
So what does that mean about you and your neighbor?.....
Calculate exactly how attracted you are to your neighbor

16. Newton’s Secret……
What is the most typical date?
Why ?????

17. Jimmy and Jane’s First Date:
Why Dinner ?
More Mass …….. Greater Attraction!

18. Why the Movie? At the theater you sit right next to each other!!
Smaller distance…….Greater Attraction!

19. The Acceleration of Gravity
What is the acceleration of gravity on the surface of the Earth? What is it on the surface of Mars?????
9.8 m/s2
How do we figure it out?
𝑎 𝐺 = 𝑚 𝑝𝑙𝑎𝑛𝑒𝑡 𝑟 2 𝐺
𝐹 𝐺 = 𝑚 1 ∗ 𝑚 2 𝑟 2 𝐺
𝐹 𝑛𝑒𝑡 =𝑚∗𝑎
Mass of Mars = 6.39*10^23 kg
Radius of Mars = 3,389 km
𝑎 𝐺 =3.7 𝑚 𝑠 2

20. How does the force of gravity change as you move away from the Earth?