If we begin from star birth, the next key stage in the star-gas-star cycle occurs when a(n) returns gas and new elements into space. The expelled gas forms a(n) that is very hot and expands in size. As the gas cools and merges with other interstellar gas, it forms a(n) . Further cooling allows the gas to become a(n) , in which star formation occur.

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)

Four identical lab carts each have a mass of 200 kg. different masses are added to the carts and the velocities are measured. all carts move to the right.

Four friends, a, b, c, and d are standing varying distances away from a speaker which is producing sound waves.