1. 18-1 Physics I Class 18 Newton’s Theory of Gravitation

2. 18-2 Forces Known to Physics

3. 18-3 Forces in Physics 1 (so far)

4. 18-4 Newton’s Theory of Gravitation

5. 18-5 Newton’s Law of Universal Gravitation

6. 18-6 Properties of Gravity

7. 18-7 If Gravity Varies As 1/r 2, Where Does g = 9.8 m/s 2 Fit In?

8. 18-8 Gravity is a Conservative Force

9. 18-9 We Have Two Formulas for Gravitational Potential Energy!

10. 18-10 Class #18 Take-Away Concepts

11. 18-11 Activity #18 Gravitation

12. 18-12 Class #18 Optional Material Part A - Kepler’s Laws of Orbits Material on Kepler’s Laws thanks to Professor Dan Sperber

13. 18-13 Kepler’s Three Laws of Planetary Motion 1. The Law of Orbits: All planets move in elliptical orbits having the Sun at one focus. 2. The Law of Areas: A line joining any planet to the Sun sweeps out equal areas in equal times. 3. The Law of Periods: The square of the period of any planet about the Sun is proportional to the cube of the semi-major axis of its orbit.

14. 18-14 Kepler’s Three Laws of Planetary Motion

15. The Law of Areas

16. The Law of Periods

17. ENERGY IN CIRCULAR ORBITS

18. 18-18 Class #18 Optional Material Part B - General Relativity Material on General Relativity thanks to Albert Einstein

19. 18-19 Where Did Newton Go Wrong? (Again!)

20. 18-20 The Principle of Equivalence

21. 18-21 The Principle of Equivalence

22. 18-22 General Theory of Relativity

23. 18-23 Black Holes

24. 18-24 If Newton’s Gravity isn’t true, why do we still use it? Massive Black Holes In Galaxies NGC 3377, NGC 3379 And NGC 4486B