Answer: 2.4 × 10⁵ Pa.
- A 2.4 × 10⁵ Pa
- B 4 × 10⁵ Pa
- C 5.6 × 10⁵ Pa
- D 3 × 10⁵ Pa
Correct answer: A. 2.4 × 10⁵ Pa
Explanation: Bernoulli (horizontal): P<sub>1</sub> + ½ρv<sub>1</sub>² = P<sub>2</sub> + ½ρv<sub>2</sub>². P<sub>2</sub> = P<sub>1</sub> + ½ρ(v<sub>1</sub>²-v<sub>2</sub>²) = 4×10⁵ + 500(4-36) = 4×10⁵ - 16000 = 384000 ≈ 3.84×10⁵ 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.