PHYS 1750: SELECTED TOPICS in PHYSICS
LECTURE 15. Gravity and Orbits.
8.5. | Newton's Law of Gravity | ||
1. | The law: Fg = GM1M2 /r 2 | ||
2. | The gravitational constant G = 6.67×10−11 N m 2 / kg 2 | ||
3. | Inverse-square nature | ||
4. | Spherical bodies | ||
a. | Outside: as if all mass concentrated at center | ||
b. | Inside: only mass inside your position has net attraction | ||
5. | Acceleration of small bodies near the Earth | ||
8.6. | Orbits and Kepler's Laws | ||
1. | Simple orbits are ellipses with Sun at one focus | ||
2. | Planet-Sun line sweeps out equal areas in equal times | ||
3. | Period squared proportional to semi-major axis cubed |