Answer: 1.6 m/s.
- A 1.6 m/s
- B 0.1 m/s
- C 0.8 m/s
- D 6.4 m/s
Correct answer: A. 1.6 m/s
Explanation: A1 v1 = A2 v2. π(2mm)² × 0.4 = π(1mm)² × v2. v2 = 0.4 × (2/1)² = 0.4 × 4 = 1.6 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.