Answer: N s m -2.
- A N s m<sup>-2</sup>
- B kg m s<sup>-1</sup>
- C N m<sup>-1</sup>
- D Pa m
Correct answer: A. N s m<sup>-2</sup>
Explanation: Viscosity has units of pascal-second, and 1 Pa s = 1 N s m<sup>-2</sup>.
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.