A circular duct of 13.4 cm diameter is fed with air by a supersonic nozzle. The stagnation pressure at the nozzle entry and static pressures at sections 5 D and 33 D downstream are 7.00, 0.245 and 0.50 bar respectively. The nozzle throat diameter is 6.46 cm. Determine (a) Mach numbers at the two sections downstream of the nozzle (b) the mean value of the skin friction between the two sections. Assume isentropic flow up to the nozzle throat and adiabatic in the rest.