Bernoulli's law is a statement of the conservation of energy in a form useful for solving problems involving fluids. For a non-viscous, incompressible fluid in steady flow, the sum of pressure, and potential and kinetic energies per unit volume is constant at any point. That is:
p + ½ρV 2 + ρgh = constant
where p is the pressure, ρ the density, V the velocity, and h the height in a gravitational field of strength g, all measured at the same point. This quantity is then constant throughout the fluid.