The image below is a birds-eye view of a mirror placed in front of some objects, represented by arrows. If an eye is located at the placed marked, which objects can be seen by the eye in the mirror?

a. All of them can be seen except the object on the left.
b. All of the objects except for the one on the right can be seen in the mirror.
c. None of the them can be seen in the mirror.
d. Every object shown in the diagram can be seen in the mirror.

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)

Why do different substances have diffrent properties

Awave has a wavelength of 7 mm and a frequency of 19 hertz. what is its speed?