A0.21-kg stone is held 1.5 m above the top edge of a water well and then dropped into it. the well has a depth of 4.9 m. (a) relative to the configuration with the stone at the top edge of the well, what is the gravitational potential energy of the stone−earth system before the stone is released? j

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)