Air enters the diffuser of a turbojet engine with a mass flow rate of 60 lb/s at 9 lbf/in², 420R, and a velocity of 750 ft/s. The pressure ratio for the compressor is 12, and its isentropic efficiency is 88%. Air enters the turbine at 2200R with the same pressure as at the exit of the compressor. Air exits the nozzle at 9 lbf/in². The diffuser operates isentropically and the nozzle and turbine have isentropic efficiencies of 92% and 90%, respectively. Use an air-standard analysis.

1) the rate of heat addition, in Btu/h.

2) the pressure at the turbine exit, in psi.

3) the compressor power input, in Btu/h.

4) the velocity at the nozzle exit, in ft/s.