An air bubble of radius r = 3 mm moves up in a viscous liquid with a constant velocity v = 0.7 cm / sec . If the density of the liquid is 1.75 gm/cc and if the viscosity of liquid (in poise) is 10x, t

Question

An air bubble of radius r = 3 mm moves up in a viscous liquid with a constant velocity v = 0.7 cm / sec . If the density of the liquid is 1.75 gm/cc and if the viscosity of liquid (in poise) is 10x, then the value of x is ____ . (Neglect the density of air in comparison to that of the liquid.)

TestHub · Accepted Answer

Stokes' law at terminal velocity: 6 π ηr v = 3 4 ​ π r 3 ρ g . η = 9 v 2 r 2 ρ g ​ = 9 × 0.7 2 × ( 0.3 ) 2 × 1.75 × 1000 ​ = 50 poise So 10 x = 50 , giving x = 5 . Answer: 5

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