Answer: 8000 Pa.
- A 4000 Pa
- B 8000 Pa
- C 16000 Pa
- D 2000 Pa
Correct answer: B. 8000 Pa
Explanation: ΔP = ½ρ(v<sub>2</sub><sup>2</sup> - v<sub>1</sub><sup>2</sup>) = 0.5 × 1000 × (25 - 9) = 8000 Pa.
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.