Answer: 1:4.
- A 4:1
- B 1:4
- C 2:1
- D 1:2
Correct answer: B. 1:4
Explanation: By continuity A₁v₁ = A₂v₂, so v<sub>wide</sub>/v<sub>narrow</sub> = A<sub>narrow</sub>/A<sub>wide</sub> = 1/4.
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.