According to Bernoulli's principle, what happens to the fluid pressure at a point where velocity increases?

• A. Pressure increases
• B. Pressure decreases
• C. Pressure remains constant
• D. It depends on the fluid

Answer: (B)

Bernoulli's principle says that along a streamline in steady, incompressible flow, the sum of static pressure and dynamic pressure remains constant. When velocity increases, the dynamic pressure term (1/2 ρ v^2) rises, so the static pressure must fall to keep the total the same. So the fluid pressure at that point decreases as speed goes up. This explains why fast-moving regions have lower pressure, such as air speeding over a wing’s surface which helps generate lift. Remember, this applies under ideal conditions: along a streamline with steady, incompressible, low-viscosity flow and minimal height change; real fluids may have losses that alter the relationship.