Universal Law of Gravitation & Archimedes' Principle
$$F = G \frac{M m}{r^2} \quad (G = 6.673 \times 10^{-11}\text{ N}\cdot\text{m}^2/\text{kg}^2)$$
- Acceleration due to Gravity: $g = \frac{GM}{R^2} \approx 9.8\text{ m/s}^2$ on Earth surface.
- Archimedes' Principle: When a body is immersed fully or partially in a fluid, it experiences an upward buoyant force equal to the weight of fluid displaced by it.
