Fluid Statics MCQ with answer and solution

Concept

Application and limitations of piezometer tube

Formula

NONE

Step-by-step solution

1. A piezometer is the simplest form of manometer used to measure liquid pressure. 2. It cannot measure negative/vacuum pressure or very high pressure because high pressures require impractically long tube heights. 3. Hence, piezometer tubes are primarily suitable for measuring moderate static liquid pressures. Answer: B

Explanation

A piezometer tube is a simple vertical pipe open at the top where liquid rises according to system pressure. High pressures would require an impractically long tube height, while vacuum pressures would draw air into the liquid system. Hence, piezometer tubes are used strictly for measuring moderate positive static pressures.

Why the other options are wrong

A) Low pressure can be measured by piezometers, but piezometers are specifically designed for moderate pressures. C) High pressure would cause the liquid column to rise to an impractically large height in the tube. D) Vacuum pressure cannot be measured because air would be sucked into the vessel through the open tube.

Shortcut

Piezometer = Low and moderate positive liquid pressure only.

Common mistake

Assuming piezometer tubes can be used to measure high or negative (vacuum) fluid pressures.