Bernoulli's PrincipleThis is an important principle involving the movement of a fluid through a pressure difference. Suppose a fluid is moving in a horizontal direction and encounters a pressure difference. This pressure difference will result in a net force, which by Newton's 2nd law will cause an acceleration of the fluid.
Bernoulli's principle states that faster moving air (higher kinetic energy) has a lower pressure, and slower moving air (lower kinetic energy) has a higher pressure. This is shown by the Venturi Tube at the right. |
Bernoulli's Principle and Lift
Using Bernoulli's principle, airplanes can produce lift. The shape of the wing (shown below) forces air going above the wing to go faster than the air going underneath it (because of the curvature of the top of the wing). As a result, the top of the wing has a lower pressure than below the wing. Since air goes from higher pressure to lower pressure, the wing is pushed upwards, thus enabling the airplane to fly.