Fluid Properties and Pressure

JKSSB Junior Engineer (Civil) · Fluid Mechanics and Hydraulics · 22 practice questions with answers and explanations: 12 Easy, 10 Medium, 0 Hard.

Sample questions

Sample Easy question 1

A floating body is in stable equilibrium when its metacentre lies:

  1. Above its centre of gravity
  2. Below its centre of gravity
  3. At the bottom of the body
  4. At the water surface only
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Answer: A. Then a small tilt produces a restoring moment.

Sample Easy question 2

The bulk modulus of water is of the order of:

  1. 0.22 GPa
  2. 2.2 GPa
  3. 2.2 MPa
  4. 220 GPa
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Answer: B. The bulk modulus is the inverse of the compressibility.

Sample Easy question 3

A differential manometer is used to measure:

  1. The difference of pressure between two points
  2. The pressure at one point only
  3. The velocity of a fluid
  4. The viscosity
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Answer: A. A piezometer measures the gauge pressure at a point.

Sample Medium question 4

The excess pressure inside a water droplet of 1 mm diameter with a surface tension of 0.073 N/m is:

  1. 584 Pa
  2. 292 Pa
  3. 146 Pa
  4. 73 Pa
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Answer: B. p = 4σ ÷ d = 4 × 0.073 ÷ 0.001 = 292 Pa. For a soap bubble the formula is 8σ ÷ d.

Sample Medium question 5

An oil of dynamic viscosity 0.002 Pa·s and density 800 kg/m³ has a kinematic viscosity of:

  1. 25 × 10⁻⁶ m²/s
  2. 0.25 × 10⁻⁶ m²/s
  3. 2.5 × 10⁻⁶ m²/s
  4. 0.002 × 10⁻⁶ m²/s
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Answer: C. ν = μ ÷ ρ = 0.002 ÷ 800 = 2.5 × 10⁻⁶ m²/s.

Sample Medium question 6

Water (μ = 0.001 Pa·s) has a velocity gradient of 100 s⁻¹ at a wall. The shear stress is:

  1. 0.01 Pa
  2. 0.1 Pa
  3. 100 Pa
  4. 1 Pa
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Answer: B. τ = μ du/dy = 0.001 × 100 = 0.1 Pa.

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