Two balls of radii r and `(r)/(2)` are released inside a deep water tank. Their initial accelerations are found to be `(g)/(2)` and `(g)/(4)` respectively. Find the velocity of smaller ball relative to the larger ball, a long time after the two balls are released. Coefficient of viscosity is given to be `eta`.

Answer

`(11)/(54)(r^(2)rhog)/(ete)`upwards