Answer: 16 m/s.
- A 4 m/s
- B 8 m/s
- C 2 m/s
- D 16 m/s
Correct answer: D. 16 m/s
Explanation: By continuity Av is constant; area falls by factor 4, so speed rises to 4 × 4 = 16 m/s.
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.