: a principle in hydrodynamics: the pressure in a stream of fluid is reduced as the speed of flow is increased
Variants of BERNOULLI'S PRINCIPLE
Ber·noul·li's principlealsoBernoulli principle
Principle that relates pressure, velocity, and height for a nonviscous fluid with steady flow. A consequence is that, for horizontal flow, as the speed of a fluid increases, the pressure it exerts decreases. Derived by Daniel Bernoulli (seeBernoulli family), the principle explains the lift of an airplane in motion. As the speed of the plane increases, air flows faster over the curved top of the wing than underneath. The upward pressure exerted by the air under the wing is thus greater than the pressure exerted downward above the wing, resulting in a net upward force, or lift. Race cars use the principle to keep their wheels pressed to the ground as they accelerate. A race car's spoilershaped like an upside-down wing, with the curved surface at the bottomproduces a net downward force.