Problem $6$ Water flows through a horizontal bed packed with sand. The bed has a diameter of $0\mathrm{.}10m$ and a length $16m.$ The mass flow rate of the liquid through the bed is $5{10}^{-4}k\frac{g}{s}.$ Calculate the pressure drop through the packed bed if the sand particles have a mean diameter of $0\mathrm{.}7mm$ and $=0\mathrm{.}38.$