chapter 3: orbits and Gravity

Comparing Density

$$density=\frac{mass}{volume}$$

Conservation of Angular Momentum

$$m\cdot v\cdot r=constant$$

Escape speed

$$v=\sqrt{\frac{2GM}{r}}$$

Newtons version of Keplers third law

$$P^2=\frac{4\pi^2}{GM}a^3$$

M = mass of orbitee (central body)

a = semi-major axis

G = gravitational constant

P = orbital period

Orbital speed (circular orbit)

$$v=\sqrt{\frac{GM}{r}}$$

Key point

If the mass of an orbitee is much larger than the mass of the orbiter, the mass of the orbiter does not matter