Four +2 μc charges are placed at the positions (10 cm, 0 cm), (−10 cm, 0 cm), (0 cm, 10 cm), and (0 cm, −10 cm) such that they form a diamond shape centered on the origin. a charge of +5 μc is placed at the origin. if the force between a +2 μc and a +5 μc charge separated by 10 cm has a magnitude of 9 n, which of the following can we say about the force on the +5 μc charge at the origin in this case?

the force on the charge at the origin is 36 n .
the force on the charge at the origin is 9 n .
the force on the charge at the origin is 18 n .
the force on the charge at the origin is 0.

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)