1. Isaac Newton

3. Initial calculations didn’t work

4. Isaac Newton Initial calculations didn’t work Placed theory in a drawer for 20 years

5. Isaac Newton Initial calculations didn’t work Placed theory in a drawer for 20 years When the comet of 1670 came, Halley convinced him to re- look at it.

6. Isaac Newton Initial calculations didn’t work Placed theory in a drawer for 20 years When the comet of 1670 came, Halley convinced him to re- look at it. Produced the Law of Universal Gravitation

7. Law of Universal Gravitation F ~ m 1 m 2 d 2 F = G x m 1 m 2 d 2 G = 6.67 x10 -11 N m 2 / kg 2

8. Universal gravitation constant (G) = 6.67 x10 -11 N m 2 / kg 2 Equals the force of attraction between two 1kg masses 1 meter apart

9. Universal Law of Gravitation Youtube http://www.youtube.com/watch?v=NPyH93vXutk http://www.youtube.com/watch?v=D5BQkdyAw8A

10. Universal gravitation constant Philipp von Jolly’s – measurement experiment Mercury Flask and a 6 ton lead ball

11. Gravitational Force The force is extremely small and for most tangible things it is two sensitive to measure attraction to one another is not measurable but the attraction to the earth is what we call weight

12. Gravitational Force It is based on the distance to the center of the earth – weigh less on a mountain Is this a new diet infomercial ???

13. Inverse Square Law

14. Book Questions 1.By how much does the gravitational force between two objects decrease when the distance between their centers is doubled, tripled, and increased tenfold? 2.Consider an apple that is at the top of a tree and is being pulled by the earths gravity with a force of 1 N. If the tree were twice as tall, would the force of gravity be only ¼ as strong?

15. Tides

17. Spring Tides Higher Than Average tides and lower than average tides

18. Neap Tides High tides lower than average and low tides higher than average

19. People Tides?