Aspring-loaded piston-cylinder device is filled with 0.35 kg of water vapor that is initially at 4 mpa and 4000c. initially, the spring exerts no force against the piston. the spring constant in the spring-force relationship is k = 0.75 and the piston diameter is d = 20 cm. the water now undergoes a process until its volume is one-half of the original volume. calculate the final temperature and the specific enthalpy of the water.

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Simple machines can a. increase force only b. decrease force only c. increase or decrease force

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)