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Fluid Mechanics
Mechanical Operations
GATE 2020
Medium

A rigid spherical particle (diameter 2×10⁻⁴ m, density 3000 kg/m³) undergoes free settling in a liquid of density 750 kg/m³ and viscosity 9.81×10⁻³ Pa·s (g=9.81 m/s²). Assuming Stokes' law, the terminal settling velocity (m/s) is

  • A2×10⁻³
  • B3×10⁻³
  • C4×10⁻³
  • 5×10⁻³

Explanation

v=gd²(ρp−ρf)/(18μ)=9.81×(2×10⁻⁴)²×2250/(18×9.81×10⁻³)=9.81×4×10⁻⁸×2250/0.17658=8.829×10⁻⁴/0.17658=5×10⁻³ m/s.

Source: GATE CH 2020 (2020)

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