Answer: Whether flow is laminar or turbulent.
- A Whether flow is laminar or turbulent
- B The absolute viscosity coefficient of the fluid
- C The static pressure head inside a pipe
- D The surface tension coefficient of the liquid
Correct answer: A. Whether flow is laminar or turbulent
Explanation: Reynolds number Re = ρvd/η. Re < 2000: laminar flow. Re > 4000: turbulent flow. 2000-4000: transition region.
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.