Q-1) Choose the Correct Answer 1- The Fahrenheit and Celsius scales are identical at (a) 32 (b) 180 (c) -40 (d) 460 (e) 273 (a) 2- In an extensive property of a thermodynamic system extensive heat is transferred (b) extensive work is done (c) extensive energy is utilized (d) all of the above (e) none of the above. 3- The condition for the reversibility of a cycle is: (a) the pressure and temperature of the working substance must not differ, appreciably, from those of the surroundings at any stage in the process (b) all the processes, taking place in the cycle of operation, must be extremely slow (c) the working parts of the engine must be friction free (d) there should be no loss of energy during the cycle of operation (e) all of the above (f) none of the above. 4- Air flows at a rate of 3 kg/s in 20 cm diameter pipe. It has a pressure of 50 bar and temperature of 100°C. It is then throttled by a valve to a pressure of 2.5 bar. Find the velocity of air before and after throttling. (a) 20.45, 40.90 (m's) (b) 10.5, 58 (m/s) (c) 30.8, 60 (m/s) Head of Department: Dr. Hanson H. Mashkoor Examiners: Best Wishes University of Misan - College of Engineering Department: Petroleum Eng Subject: Thermodynamics Exam: Final Exam 2019-2020 Stage: Year 2 Date: 13/9/2020 Time: 3 hours Examiners: Dr. Ni - Jubinawi M.Sc Noor Kadhim NOTES: (a) Answer all questions. (b) The questions are two pages) The steam table is allowed to be used 5- 0.5 kg of air at 180°C expands adiabatically to 3 times its original volume during the expansion the temperature is decreased to 20°C. Work done during expansion is 53 kJ. Find cv, cp, and R. (a) c, 0.662 kJ/kg. K. c -0.927 kJ/kg. K. R = 0.265 kJ/kg. K (b)c, = 0.432 kJ/kg. K. cp=0.31 kJ/kg K. R=0.15 kl/kg K (c) c, = 0.231 kJ/kg. K. c = 0.71 kJ/kg. K. R=0.54 kl/kg. K 6- Suppose 75 kJ of heat is supplied to a closed system at constant volume. During the next process, the system reject 80 kJ of heat isobarically, while 10 kJ of work is done on it, the cycle is completed with adiabatic process. Internal energy of system is 80 kJ. Find the amount of work transfer during the process. (a) 12 kJ (b)5 kJ (c) 20 kJ