$5-12$ A desktop computer is to be cooled by a fan whose

flow rate is $0\mathrm{.}40\frac{m^3}{m}in.$ Determine the mass flow rate of air

through the fan at an elevation of $3400$ m where the air den$-$

sity is $0\mathrm{.}7k\frac{g}{m^3}.$ Also, if the average velocity of air is not to

exceed $110\frac{m}{m}in,$ determine the minimum diameter of the

casing of the fan. Answers: $0\mathrm{.}00467k\frac{g}{s},0\mathrm{.}0569m$