\(\mathrm{NaK}(56 \% / 44 \%)\), which is an alloy of sodium and potassium, is used to cool fast neutron nuclear reactors. The NaK flows at a rate of \(\dot{m}=0.8 \mathrm{~kg} / \mathrm{s}\) through a \(D=\) 40-mm-diameter tube that has a surface temperature of \(T_{s}=435 \mathrm{~K}\). The NaK enters the tube at \(T_{m, i}=335 \mathrm{~K}\) and exits at an outlet temperature of \(T_{m, o}=397 \mathrm{~K}\). Determine the tube length \(L\) and the local convective heat flux at the tube exit.