Pressure

Pressure is the normal force per unit area exerted on a surface, or transmitted through a fluid. In a static fluid it acts equally in all directions at any given point — this isotropy is what makes fluid pressure scalar, even though force is a vector.

Atmospheric pressure at sea level is about 101 kPa. One additional atmosphere is added for every ten metres descended in water. Human lungs can comfortably push about 10 kPa; a car tyre runs at 200 kPa; a deep-ocean trench at 100 MPa; the centre of the Sun at around 10^16 Pa.