Project ForgeFluid Mechanics
Mechanical Operations
GATE 2009
Medium
The terminal settling velocity of a 6mm diameter glass sphere (density 2500kg/m³) in a viscous Newtonian liquid (density 1500kg/m³) is 100μm/s. If particle Reynolds number is small and g=9.81m/s², then the viscosity of the liquid (in Pa.s) is
- A100
- 196.2
- C245.3
- D490.5
Explanation
Vt=Δρ·g·d²/(18μ) ⟹ μ=Δρ·g·d²/(18Vt)=1000×9.81×(0.006)²/(18×100×10⁻⁶)=1000×9.81×3.6×10⁻⁵/(1.8×10⁻³)≈196.2 Pa.s.
Source: GATE CH 2009 (2009)
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