Which principle explains the relationship between speed and pressure on a surface of an aerodynamic body?

• A. Bernoulli's Principle
• B. Newton's Third Law
• C. Archimedes' Principle
• D. Pascal's Law

Answer: (A)

Bernoulli's Principle explains how increasing speed of a fluid results in lower static pressure on a surface. In aerodynamics, air speeds up as it travels over the curved upper surface of a wing, which lowers the static pressure there while the air under the wing remains comparatively slower and at higher pressure. This pressure difference pushes the wing upward, producing lift. The idea assumes steady, incompressible flow along a streamline and helps describe why fast-moving air exerts less pressure than slower-moving air nearby. In real wings, viscosity and flow separation modify the exact distribution, but the inverse relationship between speed and pressure remains a core way to understand lift. Other principles describe different phenomena: Newton's Third Law is about action–reaction forces, Archimedes' Principle is about buoyancy in fluids, and Pascal's Law concerns pressure transmission in enclosed fluids.