The diagram shows a syringe containing air. The end of the syringe has been sealed. The volume of air is 150cm^3, at a pressure of 100kN/m^2 (100kPa). a). Explain, in terms of the movement of molecules, how the air exerts a pressure on the inside surface of the syringe.

b). A force is now applied to the piston. This compresses the air to 120cm^3. The temperature remains constant. What is the pressure of the air now?

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)