Answer: P + ½ρv² + ρgh = constant along a streamline.
- A P + ½ρv² + ρgh = constant along a streamline
- B P = ρgh holds at every point regardless of flow speed
- C P + ρv stays constant along the streamline
- D P equals ½ρv² with no dependence on height
Correct answer: A. P + ½ρv² + ρgh = constant along a streamline
Explanation: Bernoulli's equation: P + ½ρv² + ρgh = constant. It is an expression of energy conservation (work-energy theorem) for fluid flow.
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.