$2$: Two materials $($wrought iron, $ks=0\mathrm{.}046mm,$ and galvanized iron, $ks=0\mathrm{.}15mm)$ are being

considered for a new pipeline. The expected discharge is $0\mathrm{.}15m\frac{3}{s}.$ Both the headloss and cost are

sought for. Wrought iron pipe costs $5$ cents more than the galvanized iron pipe for every meter length

of the pipe. Determine the tradeoff between the cost and the energy head for pipe diameters of $200$

$mm$ and $150mm.$ Take the temperature as $15C.$