A critical flow nozzle is used to measure the mass flow rate of air (?=1.4, R=287J/kg*K). The pipe diameter is 3cm and the nozzle diameter is 1cm. The pressure downstream of the nozzle is 100kPa (abs) and the pressure in the pipe upstream of the nozzle is 500kPa (abs). The upstream temperature is 400K. Estimate the mass flow rate assuming that the discharge coefficient, C, is unity.