A small steel ball of mass ' M ', radius ' R ' and density ' $\rho$ ' falls with terminal velocity through a tube filled with glycerine of density ' $\sigma$ '. The viscous force acting on the steel ball is ( $\mathrm{g}=$ acceleration due to gravity)

If the shape of the liquid surface is curved, then the

A spherical liquid drop of radius R is divided into 64 equal droplets. If surface tension is $T$ then the work done in this process will be

A glass capillary of radius 0.35 mm is inclined at $60^{\circ}$ with the vertical in water. The length of water column in the capillary tube is (surface tension of water $=7 \times 10^{-2} \mathrm{Nm}^{-1}$, acceleration due to gravity $=10 \mathrm{~m} / \mathrm{s}^2, \cos 0^{\circ}=1$, $\cos 60^{\circ}=0.5$, density of water $=1 \mathrm{gram} / \mathrm{cm}^3$ )