GATE 2022 AG – Question 60
A .68 mm falling ball traverses10 cm of sunflower oil in 44.5 s. Oil density921 kg/m³; ball density2420 kg/m³; g=9.81 m/s². Find dynamic viscosity in Pa s, to three decimals.
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Correct answer: 0.165 to 0.172
Explanation
Terminal speed is .10/44.5=.00224719 m/s. Stokes balance gives $\mu=g d^2(\rho_b-\rho_o)/(18v)$. Substitution gives .168103 Pa s, or **.168 Pa s**. This assumes terminal laminar settling and negligible wall/end corrections, as in the stated viscometer model.
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