Bernoulli's Theorem

[1] In a stream of liquid, the sum of elevation head, pressure head, and velocity remains constant along any line of flow provided no work is done by or upon liquid on course of its flow; decreases in proportion to energy lost in flow.
[2] The law that for a non-viscous, incompressible fluid in steady flow, the sum of the pressure and kinetic energies per unit volume is constant at any point. It is a fundamental law of fluid mechanics.