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GATE 2018 CE (CE1) – Question 42

Fluid Mechanics · Properties of fluids, fluid statics · 2 marks · Multiple choice

A closed tank has bottom mercury layer 0.5 m thick (SG 13.6), water layer 2.0 m thick above it, and oil layer 3.0 m thick (SG 0.6) above the water. Pressurized air lies above the oil. Bottom gauge pressure is 196.2 kN/m². Water density is 1000 kg/m³ and g = 9.81 m/s². Air-space gauge pressure is ______.

  1. 92.214 kN/m²
  2. 95.644 kN/m²
  3. 98.922 kN/m²
  4. 99.321 kN/m²

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Correct answer: (A) 92.214 kN/m²

Explanation

The equivalent water depth of the liquids is $13.6(0.5)+2+0.6(3)=10.6$ m. Air gauge pressure is bottom pressure minus this hydrostatic increment: $196.2-9.81(10.6)=92.214$ kN/m² (A).