A water main $0\mathrm{.}6$ m diameter at $15C$ discharges $0\mathrm{.}45\frac{m^3}{s}.$ The surface of the pipe is rough and may be taken as having protuberances of effective height $1\mathrm{.}25$ mm $,$ calculate the loss of head per unit length. Calculate also the loss of head per unit length in an $18$ mm diameter pipe of the same material in which water at $5C$ is flowing at a velocity of $1\mathrm{.}5\frac{m}{s}.$