Pressure

Pressure is calculated as:

$p = \frac{F}{A}$

where $F$ is the force (N) and $A$ is the area (m$^2$).

In liquids, pressure increases with depth:

$p = \rho g h$

where $\rho$ is density (kg/m$^3$), $g$ is gravitational field strength (N/kg), and $h$ is the depth (m).

Pressure acts in all directions at a point in a liquid. A sharp knife cuts well because the small area of the blade gives a high pressure for a given force.