(Solved): 2) (50 pts) Air is contained in a vertical piston-cylinder assembly fitted with an electrical r ...

2) (50 pts) Air is contained in a 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 $45\mathrm{kg}$ and area of $0,09{\mathrm{m}}^2$. Electric current passes through the resistor, and the volume of the air slowly increases by $0,045{\mathrm{m}}^3$ while its pressure remains constant. The mass of the air is $0,27\mathrm{kg}$, and its specific internal energy increases by $42\mathrm{kJ}/\mathrm{kg}$. The air and piston are at rest initially and finally. The piston-cylinder system is well insulated. Friction between the piston and cylinder wall can be ignored, and the local acceleration of gravity is $\mathrm{g}=9,81\mathrm{m}/{\mathrm{s}}^2$. Determine the electrical work performed by the resistor, in kJ. (See figure 2)