Calculate the energy spent in spraying a drop of mercury of r radius into N droplets all of same size. If the surface tension of mercury is T.

∆U = N(4π12)T-4πR2T       = 4πT(Nr12-R2)-----------------(i)By mass conservationN(23πr13ρ) =43πR3ρr1 = R(N)13------------(ii)Substitute r1 from equation (ii) in equation (i).∆U = 4πR2T(N13-1)