Second Law of Thermodynamics topics include: Second law of thermodynamics, cyclic heat engine, kelvin planck statement, refrigerator and heat pump, carnot theorem, absolute temperature scales and clausius theorem. The second law of thermodynamics is a physical law that describes the direction of spontaneous processes and the interconversion of heat and energy.  It states that: Heat always flows from hotter to colder regions of matter. Entropy, the degree of randomness or disorder in a system, tends to increase over time. Every energy transfer increases entropy and reduces the amount of... Show more

Second Law of Thermodynamics topics include: Second law of thermodynamics, cyclic heat engine, kelvin planck statement, refrigerator and heat pump, carnot theorem, absolute temperature scales and clausius theorem.

The second law of thermodynamics is a physical law that describes the direction of spontaneous processes and the interconversion of heat and energy. 

It states that:
Heat always flows from hotter to colder regions of matter.
Entropy, the degree of randomness or disorder in a system, tends to increase over time.
Every energy transfer increases entropy and reduces the amount of usable energy available to do work.
It is impossible for heat transfer from a reservoir to completely convert to work in a cyclical process. 

The second law of thermodynamics is also known as the Law of Increased Entropy. It limits the direction of heat transfer and the achievable efficiencies of heat engines. For example, it is impossible to convert heat energy to mechanical energy with 100% efficiency. 

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Thermodynamics Practice Test: Second Law of Thermodynamics

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25 Questions

1. What does a refrigerant do?

all of the mentionedevaporates in the evaporatorabsorbs latent heat of vaporization form the body which is cooledabsorbs the heat leakage into body from surroundings

2. If one of the Kelvin-Planck’s or Clausius’ statement is violated, then other is also violated.

TrueFalseDon't KnowMaybe

3. What is the relation between COP of heat pump and refrigerator?

COP of pump=COP of refrigerator – 2COP of pump=COP of refrigerator + 2COP of pump=COP of refrigerator – 1COP of pump=COP of refrigerator + 1

4. At absolute zero, an isotherm and an adiabatic are identical.

Don't KnowTrueFalseMaybe

5. The external irreversibility occurs at the system boundary.

Don't KnowMaybeTrueFalse

6. The operation of a machine that utilizes the internal energy of only one TER, thus violating second law is called

PMM2PMM0none of thesePMM1

7. The continual motion of a movable device in the complete absence of friction is known as

PMM1PMM0PMM3PMM2

8. The correct sequence of the processes taking place in a carnot cycle is

isothermal -> isothermal -> adiabatic -> adiabaticadiabatic -> adiabatic -> isothermal -> isothermalisothermal -> adiabatic -> isothermal -> adiabaticadiabatic -> isothermal -> adiabatic -> isothermal

9. In a cryogenic experiment you need to keep a container at -125°C although it gains 100 W due to heat transfer. What is the smallest motor you would need for a heat pump absorbing heat from the container and rejecting heat to the room at 20°C?

95.84 kW98.84 kW97.84 kW99.84 kW

10. Processes inside a thermal energy reservoir are quasi-static.

Don't KnowFalseTrueMaybe

11. Which of the following is true?

all of the mentionedmechanical irreversibility is due to finite pressure gradientthermal irreversibility is due to finite temperature gradientchemical irreversibility is due to finite concentration gradient

12. Heat is transferred to a heat engine from a furnace at a rate of 80 MW. If the rate of waste heat rejection to a nearby river is 50 MW, determine the net power output for this heat engine.

60 MW30 MW50 MW40 MW

13. For a reversible refrigerator, Coefficient of Performance is given by

T1/(T2-T1)T2/(T2-T1)T2/(T1-T2)T1/(T1-T2)

14. According to Carnot’s theorem, all heat engines operating between a given constant temperature source and sink, none has a higher efficiency than a reversible engine.

TrueDon't KnowFalseMaybe

15. A cyclic machine, as shown below, receives 325 kJ from a 1000 K energy reservoir. It rejects 125 kJ to a 400 K energy reservoir and the cycle produces 200kJ of work as output. Is this cycle reversible, irreversible, or impossible?

impossibleirreversiblenone of thesereversible

16. Boiler, turbine, condenser and pump together constitute a heat engine.

MaybeTrueDon't KnowFalse

17. An air-conditioner provides 1 kg/s of air at 15°C cooled from outside atmospheric air at 35°C. Estimate the amount of power needed to operate the air-conditioner.

1.39 kW1.29 kW1.19 kW1.09 kW

18. Example of reversed heat engine is

both of the mentionedheat pumprefrigeratornone of these

19. Which if the following statements are true for a mechanical energy reservoir(MER)?

all of the mentionedit is a large body enclosed by an adiabatic impermeable wallstores work as KE or PEall processes within an MER are quasi-static

20. According to Kelvin-Planck statement, it is ____ for a heat engine to produce net work in a complete cycle if it exchanges heat only with bodies at ____

possible, single fixed temperaturepossible, changing temperatureimpossible, single fixed temperatureimpossible, changing temperature

21. The efficiency of a general cycle will be _____ the efficiency of a reversible cycle.

equal to or greater thanequal toless thanequal to or less than

22. Which of the following statements are true?

COP for both refrigerator and pump cannot be infinitywork input for both refrigerator and pump is greater than zeroall of the mentioneda heat pump provides a thermodynamic advantage over direct heating

23. In defining the temperature scale, the standard reference point is taken as

boiling point of watertriple point of waternone of thesezero kelvin

24. Kelvin-Planck’s and Clausius’ statements are

virtually two parallel statements of second lawviolation of one doesn’t violate the othernone of thesenot connected to each other

25. A reversible process coincides with a quasi-static process.

MaybeDon't KnowFalseTrue