## Question

An area bubble of radius 1mm is allowed to rise through a long cylindrical column of a viscous liquid of radius 5 cm and travels at a steady rate of 2.1 cm per sec. If the density of the liquid is 1.47 g per cc, find its velocity. Assume g = 980 cm/sec^{2} and neglect the density of air.

### Solution

1.524 poise

Hence due to force of buoyancy the bubble will move up and so viscous force which opposes the motion well act downward and as weight of bubble is zero, in dynamic equilibrium, *Th* = *F*,

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