Consider a natural-gas pipe-line of inner diameter \(60 \mathrm{~cm}\) and length \(16 \mathrm{~km}\). The pressure at the inlet is \(7 \mathrm{~atm}\) and the temperature is \(20^{\circ} \mathrm{C}\). The inlet velocity is \(1.2 \mathrm{~m} / \mathrm{s}\). Find the exit pressure and the conditions at the exit.

(a) Assume isothermal flow.

(b) Assume adiabatic flow.