GATE 2017 ME (ME2) – Question 49
The arrangement shown measures gas speed V in a pipe. Gas density is 1 kg/m³, manometer water density is 1000 kg/m³, g = 9.81 m/s² and V = 20 m/s. The differential height h between manometer arms is ______ mm.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 19 to 21
Explanation
The Pitot-static pressure difference isρgas V²/2=1·20²/2=200Pa. The differential manometer gives Δp=(ρwater−ρgas)gh. Thus h=200/(999·9.81)=0.02041m=**20.41mm**. Neglecting gas density in the manometer changes only the last digits.