What is an example illustrating gravitational potential energy transforming into kinetic energy? A.
A hammer dropped off a roof accelerates as it falls.
B.
A burning log heats a container of water.
C.
A rubber band becomes harder to pull as it is stretched farther.
D.
Cells in the body convert food molecules.

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)