A liquid drop having surface energy $E$ is spread into 729 droplets of same size. The final surface energy of the droplets is

A water drop of $0.01 \mathrm{~cm}^3$ is squeezed between two glass plates and spreads in to area of $10 \mathrm{~cm}^2$. If surface tension of water is 70 dyne $/ \mathrm{cm}$ then the normal force required to separate glass plates from each other will be

' $n$ ' small water drops of same size (radius $r$ ) fall through air with constant velocity V. They coalesce to form a big drop of radius R . The terminal velocity of the big drop is

A small metal sphere of density $\rho$ is dropped from height $h$ into a jar containing liquid of density $\sigma(\sigma>\rho)$. The maximum depth up to which the sphere sinks is (Neglect damping forces)