What is meant by the statement that the linear expansivity of copper is 0.17/k?
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steel bars each of length 3m at 29°c are to be used for constructing a rail line. if the linear expansivity of steel is 1.0×10⁻⁵/k. calculate the safety gap that must be kept between successive bars, if the highest temperature expected is 40°c

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)