Which of the following statements regarding orbits is true?
A. In an orbit, the satellite and the central body are the two foci of the
ellipse.

B. The Sun and a planet are at the two foci of an orbit.

C. The central body is located at one focus of the ellipse describing
the orbit.
D. In an elliptical orbit, there is one focus and the satellite is located
there.

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)