Where the speed is high the pressure will be low why?

whenever there is reduction in cross section area we experience increase in speed and decrease in pressure like in case of a nozzle. This can be proved by the help of Conservation of mass equation i.e. Av = cont. and bernoulli's equation which gives pressure is inversely proportional to velocity. we also have P = F/A that means decrease in area increase of pressure here it may look contradictory but the fact of matter is force is also changing with change of area of cross section, we also know that velocity is inversely proportional to area.

ρ

 

In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.[1][2] The principle is named after Daniel Bernoulli who published it in his book Hydrodynamica in 1738.[3] Bernoulli's principle can be applied to various types of fluid flow, resulting in various forms of Bernoulli's equation; there are different forms of Bernoulli's equation for different types of flow. The simple form of Bernoulli's equation is valid for incompressible flows (e.g. most liquid flows and gases moving at low Mach number). More advanced forms may be applied to compressible flows at higher Mach numbers (see the derivations of the Bernoulli equation).