2. Understanding Newton and the tree… ?

3. How can the moon be falling toward Earth??? A Centripetal Acceleration… acceleration that is “center seeking” For mass to be accelerating there must be… To find the centripetal Force, we need to be able to find centripetal acceleration…

4. R R θ θ b bRbRbRbR ΔvvΔvvΔvvΔvv = Finding the centripetal acceleration… If Δt  0 (to find instantaneous acceleration) then… v v a = Δv/ Δt … essentially the change in velocity v v ΔvΔv a = Δv/ Δt… so… b*v R ΔvΔvΔvΔv = acacacac v2Rv2Rv2Rv2R =

5. Is this the same for anything to travel in a circle…

6. Centripetal vs. Centrifugal

7. So What Provides the Centripetal Force Necessary for orbit?

8. What does the Gravity force come from??? ? Ancient thinkers say… Newton says… Einstein…

9. How does gravity “work” then…? Use your brain and with the facts you know to decide what variables would define the strength of gravity… F g = ?

10. Distance Force of Gravity On the road to an equation

11. http://www.cornillot.com/images/graphics/Planets/jupiter.jpg 300 x Distance 300 x Force of Gravity

12. Distance http://www.cornillot.com/images/graphics/Planets/jupiter.jpg Gravitational F FF Force is DIRECTLY proportional to the PRODUCT of the M MM Masses Force ~ Mass1 · Mass2 300 x 80 x 24,000 x Force of Gravity

13. 200 lbs ? lbs Radius 2·Radius What about the distance between the masses?

14. Distance = 1 R 2 R 3 R 4 R Gravity = 1 g 1/4 g 1/9 g 1/16 g GRAVITY – “like a force field” Force ~ 1 / Dist.2

15. GRAVITY – a mathematical look How fast is the moon accelerating? a = v 2 r t = 27.3 days r = 3.84 x 10 8 m Compare that to “g” on Earth… Force ~ 1 / Dist.2

16. Newton’s hypothesis of Universal Gravitation Force = G Mass 1 · Mass 2 Distance 2 Distance 2 What’s up with the “G”

17. m2m2 m1m1 Weight Gravitational Force Distance Force = G Force = G m1 ·m2R2m1 ·m2R2m1 ·m2R2m1 ·m2R2G = 6.67 x 10-11

18. Mass of Earth Mass of Earth 5,975,800,000,000,000,000,000,000 kg (13,174,000,000,000,000,000,000,000 lbs) ? How do they know that?

19. http://www.scarlett.ru/source/models/hires/sc-214/sc-214-white.jpg

20. m2m2m2m2 1 kg Distance = 6,378,160 meters Gravitational Force = 9.8 N Force = G Force = G m1 ·m2R2m1 ·m2R2m1 ·m2R2m1 ·m2R2 9.8 = 6.67 x 10 -11 9.8 = 6.67 x 10 -11 1 ·m 2 6,378,160 2 m2 = 5.975,8 x 10 24 kg

21. Distance = 6,378,160 meters How do they know that? Good ole “Eratosthenes”

22. Force = G Mass 1 · Mass 2 Distance 2 Distance 2

23. IMAX – Cosmic Voyage

24. F g = G m 1 m 2 r 2 How many masses are in the Universe…