An incompressible fluid flows through a pipe that becomes narrower in one section. The fluid speed increases in that region to maintain:
- A. Constant pressure
- B. Constant energy
- C. Constant mass flow rate
- D. Constant volume
Explanation
The same mass must pass every cross section each second, so where the area falls the speed must rise in proportion, which is the equation of continuity and is simply conservation of mass applied to a fluid. Pressure certainly does not stay constant; it falls in the constriction, which is Bernoulli's principle. This is why a thumb over a hose makes the water squirt further.