A converging-diverging nozzle exits smoothly to sea-level standard atmosphere. It is supplied by a 40-m3 tank initially

Question:

A converging-diverging nozzle exits smoothly to sea-level standard atmosphere. It is supplied by a 40-m3 tank initially at 800 kPa and 100°C. Assuming isentropic flow, estimate
(a) The throat area; and
(b) The tank pressure after 10 sec of operation. NOTE: The exit area is 10 cm2 (this was omitted in the first printing).