Four kilograms of an ideal gas are contained within a piston-cylinder device. the gas undergoes a polytropic process with a polytropic exponent of 1.5. the initial pressure is 3 bars, the initial volume is 0.1 m3, and the final volume is 0.2 m3. if the change in specific internal energy of the gas during the process is -4.6 kj/kg, determine the net heat transfer, in kj.