1st Law of Thermodynamics and Evaluating Work 1. Two kilograms of oxygen gas (O2) is in a rigid tank with a volume of 0.8 m. The tank is fitted with a paddle wheel that transfers energy to the gas by work at a constant rate of 16 watts (W) for 1 hour. After the process, the specific internal energy of the O2 is increased by 25 kJ/kg (this is the Au). If no changes in kinetic and potential energy occur, determine a. The specific volume at the final state, in m/kg. (Answer: v = 0.4 m/kg) b. The energy transfer by work, in kJ. (Answer: W = -57.6 kJ) c. The energy transfer by heat transfer, in kJ, and the direction of the heat transfer. (Answer: Q=-7.6 kJ) Paddle wheel 02 Gas 2. A gas in a piston-cylinder assembly initially at p = 200 kPa is compressed to p2 = 800 kPa and total volume of V = 0.02 m, in a process during which the relation between pressure and volume is pV 1.3 = constant. The mass of the gas is 0.2 kg. If the specific internal energy of the gas increases by 100 kJ/kg during the process, determine the heat transfer, in kJ. Kinetic and potential energy changes are negligible. (Answer: Q = 5.4 kJ)