1. A closed system containing 5-kg of air undergoes an isothermal process from 400 kPa and 300 C to 80 Kpa. Determine the initial volume of this system, the work done and the heat transfer during this process. 10 points 2. If you ever slapped someone or got slapped yourself, you probably remember the burning sensation. Imagine you being slapped by an angry person, which caused the temperature of the affected area of your face to rise by 2.7 C. Assuming the slapping hand has a mass of 1 kg and abount 0.2 kg of the tissue on the face and the hand is affected by the incident, estimate the velocity of the hand just before impact. Take the specific heat of the tissue to be 3.8 kJ/kg *K 10 points. 3. A mass of 3 kg of saturated liquid-vapor mixture of water is contained in a piston-cylinder device at 200 kPa. Initially, 1.5 kg of water is in the liquid phase and the rest is in the vapor phase. Heat is now transferred to the water, and the piston, which is resting on a set of stops, starts moving when the pressure inside reaches 700 kPa. Heat transfer continues until the total volume increases by 20 percent. Determine (a) the initial and final temperatures, (b) the mass of liquid water when the piston first starts moving, and (c) the work done during this process. Also, show the process on P-V diagram. 15 points 4. The diffuser in a jet engine is designed to decrease the kinetic energy of the air entering the engine compressor without any work or heat interactions. Calculate the velocity at the exit of a diffuser when air at 120 kPa and 35 C enters it with a velocity of 320 m/s and the exit state is 210 kPa and 95 C. 15 points 5. Air enters the compressor of a gas-turbine plant at ambient conditions of 100 kPa and 25 C with a low velocity and exits at 1 MPa and 350 C with a velocity of 80 m/s. The compressor is cooled at a rate of 1800 kJ/min, and the power input to the compressor is 280 kW. Determine the mass flow rate of air through the compressor. 15 points 6. A desktop computer is to be cooled by a fan. The electronic components of the computer consume 60 W of power under full load conditions. The computer is to operate in environments at temperatures up to 50 C and at elevations up to 3200 m where the average atmospheric pressure is 66 kPa. The exit temperature of air is not to exceed 60 C to meet the reliability requirements. Also, the average velocity of air is not to exceed 110 m/min at the exit of the computer case where the fan is installed to keep the noise level down. Determine the flow rate of the fan that needs to be installed and the diameter of the casing of the fan. 15 points 7. A household refrigerator that has a power input of 500 W and a COP of 1.8 is to cool 5 large watermelons, 10 kg each, to 8 C. If the watermelons are initially at 26 C, determine how long it will take for the refrigerator to cool them. Watermelons can be treated as water whose specific heat is 4.2 kJ/kg C. 20 points