Air is contained in a vertical piston-cylinder assembly by a piston of mass 50 kg and having a face area of 0.01 m2. The mass of the air is 5 g, and initially the air occupies a volume of 5 L. The atmosphere exerts a pressure of 100 kPa on the top of the piston. The volume of the air slowly decreases to 0.002 m3 in a quasi-equilibrium process as the specific internal energy of the air decreases by 260 kJ/kg. Neglecting friction between the piston and the cylinder wall, determine the heat transfer to the air in kJ.