THE SECOND LAW OF THERMODYNAMICS

Questions 1- 3 are multiple choice but note that more than one option may be correct.

Question 1. When a thermodynamic system has undergone a cyclic process:
(a) the net work done must be zero
(b) the system and surroundings must have returned to their original state
(c) the internal energy of the system returns to its original value
(d) the heat supplied must be equal to the heat rejected.

Question 2. The second law of thermodynamics is:
(a) provable by experiment
(b) deduced from observations
(c) provable by mathematics
(d) a statement of what is 'not possible'.

Question 3. Any perpetual motion machine must violate:
(a) the first law of thermodynamics
(b) the second law of thermodynamics
(c) the first and second law of thermodynamics
(d) either the first or second law of thermodynamics.

Question 4. State either the Kelvin-Planck or the Clausius form of the second law of thermodynamics.

Question 5. A heat engine receives 150 kJ of heat energy from a hot reservoir and rejects 50 kJ of heat to a heat sink. Calculate:
(a) the amount of work delivered
(b) the maximum thermal efficiency of the heat engine.

Question 6. A refrigerator consumes 30 kJ of work energy from the surroundings, and extracts 40 kJ of heat energy from the cold sink. Assuming there are no losses, calculate:
(a) the heat delivered to the hot reservoir
(b) the coefficient of performance of the refrigerator.

Question 7. A heat pump extracts 200 kJ of heat from the cold reservoir and delivers 500 kJ of heat to the hot reservoir. Assuming there are no energy losses, calculate:
(a) the work supplied to the heat pump
(b) the coefficient of performance of the heat pump.