Question

Question Two (10 Marks] Air is contained in vertical piston-cylinder assembly fitted with an electrical resistor. The atmosphere exerts a pressure of 1 bar on the top of the piston, which has a mass of 45 kg and a face area of 0.09 m². Electric current passes through the resistor, and the volume of the air slowly increases by 0.45 m while its pressure remains constant. The mass of the air is 0.27 kg. and its specific internal energy increases by 42 kJ/kg. The air and piston are at rest initially and finally. The piston-cylinder material is a ceramic composite and thus a good insulator. Friction between the piston and cylinder wall can be ignored, and the acceleration due to gravity is 3 - 9.81m/s. Determine the amount of heat transferred from the resistor to the air in kj for a system consisting of a) the air alone b) the air and the piston

Answer 1

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