Answer: ½ρv².
- A ½ρv²
- B ρv²
- C ρv
- D 2ρv²
Correct answer: A. ½ρv²
Explanation: Dynamic pressure = ½ρv². In Bernoulli's equation: static pressure P + dynamic pressure + hydrostatic pressure = constant. The dynamic pressure represents kinetic energy per unit volume.
Since the same volume of fluid must pass every cross-section per second (continuity), the fluid speeds up where the pipe narrows; Bernoulli's equation then says this faster-moving fluid has lower pressure - the principle behind a venturi meter and an aircraft wing's lift.
Concept context
Pressure, buoyancy, Bernoulli equation, viscosity, and surface tension.