For an incompressible fluid (density \( \rho \)) at rest, the pressure \( p \) varies linearly with fluid depth \( z \). This means that the pressure along a horizontal plane (at a certain depth \( z \) is constant.

* Derivation of the pressure \( P(z) \) at the bottom of a cylinder of liquid with cross-sectional area \( A \)*

The fluid pressure \( P(z) \) can be written as:

Derivation:

* Derivation of the pressure \( P(z) \) at the bottom of a cylinder of liquid with cross-sectional area \( A \)*