Answer: 10 m/s.
- A 5 m/s
- B 10 m/s
- C 20 m/s
- D 7 m/s
Correct answer: B. 10 m/s
Explanation: By Torricelli theorem, v = √(2gh) = √(2·10·5) = 10 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.