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Chapter Eleven – Thermodynamics

This chapter is about behavior of gases under different circumstances,tems related heat and energy also laws of thermodynamics.internal energy is the sum of all forms of molecular energy present in the system.temperature is constant in isothermal process whereas in adiabatic process insulation is present due to which,thermal energy neither leave or enter in the system.a device which converts a part of thermal energy to work is called heat engine.

Q 11.1: Estimate the average speed of nitrogen molecules in air under standard conditions of pressure and temperature.

Q 11.2: Show that ratio of the root mean square speeds of molecules of two different gases at a certain temperature is equal to the square root of the inverse ratio of their masses.

Q 11.3: A sample of gas is compressed to one half of its initial volume at constant pressure of 1.25 * 10(5) Nm(-2). During the compression, 100J of work is done on the gas. Determine the volume of the gas.

Q 11.4: A thermodynamic system undergoes a process in which its internal energy decreases by 300J. If at the same time 120J of work is done on the system, find work done on the system, find the heat lost by the system.

Q 11.5: A Carnot engine utilize an ideal gas. The source temperature is 227 degree Celsius and the sink is 127 degree Celsius. Find the efficiency of the engine. Also find the heat input from the source and the heat rejected to the sink when 10000J of work is done.

Q 11.6: A reversible engine works between two temperatures whose difference is 100 degree Celsius. If it absorbs 746J of heat from the source and rejects 546J to the sink, calculate the temperature of the source and the sink.

Q 11.7: A mechanical engineer develops and engine, working between 327 degree Celsius and 27 degree Celsius and claim correctly? Explain.

Q 11.8: A heat engine performs 100J of work and at the same time rejects 400J of heat energy to the cold reservoir. What is the efficiency of the engine?

Q 11.9: A Carnot engine whose low temperature reservoir is at 7 degree Celsius has an efficiency of 50%. It is desired to increase the efficiency to 70%. By how many degrees the temperature of the source be increased?

Q 11.10: A steam engine has a boiler that operates at 450K. The heat changes water into steam, which drives the piston. The exhaust temperature of the outside air is about 300K. What is the maximum efficiency of the steam engine?