5 Enrichment: Bernoulli's principle

Bernoulli's principle

• relates the pressure of a fluid to its speed: where the speed of a fluid increases, its pressure decreases. Application: the wing of an aeroplane has a curved upper surface and a flat lower surface, so air flows faster over the top than below it.
• The pressure above the wing (P₁) is therefore lower than below (P₂); the pressure difference gives an upward lift force that supports the aircraft.