1. A piston-cylinder arrangement contains 250g of air at a pressure of 2 bar and a...

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1. A piston-cylinder arrangement contains 250g of air at a pressure of 2 bar and a temperature of 25C, respectively. The specific heat at constant volume is C -0.718 kJkg K. If the diameter of the cylinder is 0.25m a. Calculate the height of the piston from the base of the cylinder pVmRT = ndh h = U=Q-W U=MCAT AT = 55.7 = 353.7K mRT dp P2V2 = P3V3 b. The piston is locked in place and 10kJ of heat is added. Determine the new temperature and pressure of the air in the cylinder. 10x10 250x0.718 Q mcy P = = 0.25x257x298 0.252 = PXT 2x533.7 T 298 -x2x10 = 2.37 bar TX0.25 2.18m 55.7 T 298 + c. The piston undergoes a polytropic expansion (n=1.23) to a pressure of 1bar. Calculate the work done. V= 4 = 0.049m (20 marks) d. If the piston's movement is locked again, how much heat is required to increase the pressure to 1.45bar and what is the new temperature? 1. A piston-cylinder arrangement contains 250g of air at a pressure of 2 bar and a temperature of 25C, respectively. The specific heat at constant volume is C -0.718 kJkg K. If the diameter of the cylinder is 0.25m a. Calculate the height of the piston from the base of the cylinder pVmRT = ndh h = U=Q-W U=MCAT AT = 55.7 = 353.7K mRT dp P2V2 = P3V3 b. The piston is locked in place and 10kJ of heat is added. Determine the new temperature and pressure of the air in the cylinder. 10x10 250x0.718 Q mcy P = = 0.25x257x298 0.252 = PXT 2x533.7 T 298 -x2x10 = 2.37 bar TX0.25 2.18m 55.7 T 298 + c. The piston undergoes a polytropic expansion (n=1.23) to a pressure of 1bar. Calculate the work done. V= 4 = 0.049m (20 marks) d. If the piston's movement is locked again, how much heat is required to increase the pressure to 1.45bar and what is the new temperature?