An air bubble of diameter 6 mm rises steadily through a solution of density 1750 kg m - 3 at the rate of 0 . 35 cm s - 1 . The co-efficient of viscosity of the solution (neglect density of air) is ________ Pas (given, g = 10 m s - 2 ).

Step-by-step solution

The bubble is moving with a constant velocity so the net force acting on the body is zero. Stokes' law defines the drag force which is given by F = 6 π η r v The buoyant force is given by B = V ρ g = 4 3 π r 3 ρ g Hence, it can be written that 4 3 π r 3 ρ g = 6 π η r v ⇒ η = 2 r 2 ρ g 9 v = 2 × 3 × 10 - 3 2 × 1750 × 10 9 × 0 . 35 × 10 - 2 = 10   Pas