Newton’s law of universal gravitation: Every two masses attract each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.
Gravitational force (F) = \large\displaystyle \frac{\mathrm{G}\mathrm{m}_1\mathrm{m}_2}{\mathrm{r}^2}
Acceleration due to gravity at the surface (g) = \large\displaystyle \frac{\mathrm{G}\mathrm{M}}{\mathrm{R}^2}
Gravitational potential energy (U) = \large\displaystyle -\frac{\mathrm{G}\mathrm{M}\mathrm{m}}{\mathrm{r}}
Gravitational potential (V) = \large\displaystyle -\frac{\mathrm{G}\mathrm{M}}{\mathrm{r}}
Escape speed (vₑ) = \large\displaystyle \sqrt{\frac{2\mathrm{G}\mathrm{M}}{\mathrm{R}}}
Orbital speed (vₒ) = \large\displaystyle \sqrt{\frac{\mathrm{G}\mathrm{M}}{\mathrm{r}}}
Acceleration due to gravity at height h (gₕ) = \large\displaystyle \mathrm{g}\left(\frac{\mathrm{R}}{\mathrm{R}+\mathrm{h}}\right)^2
Acceleration due to gravity at depth d (g_d) = \large\displaystyle \mathrm{g}\left(1-\frac{\mathrm{d}}{\mathrm{R}}\right)
Orbital time period (T) = \large\displaystyle 2\pi\sqrt{\frac{\mathrm{r}^3}{\mathrm{G}\mathrm{M}}}
Total orbital energy (E) = \large\displaystyle -\frac{\mathrm{G}\mathrm{M}\mathrm{m}}{2\mathrm{r}}
Kepler’s third law: The square of a planet’s or satellite’s orbital period is proportional to the cube of its orbital radius.
\large\displaystyle \frac{\mathrm{T}^2}{\mathrm{r}^3}=\frac{4\pi^2}{\mathrm{G}\mathrm{M}}