Thermodynamics: Heat and Energy Transfer in Engineering Systems

Question 1

In thermodynamics, an adiabatic process is characterized by:

Accepted Answer

Absence of heat exchange with the surroundings

Answer

Exclusive performance of work on the system

Answer

Increase in system entropy

Question 2

The first law of thermodynamics states that:

Accepted Answer

Energy cannot be created or destroyed

Answer

Energy can be created or destroyed

Answer

Entropy always increases

Answer

Heat flows from cold to hot

Question 3

The SI unit of energy is the:

Accepted Answer

Joule

Answer

Watt

Answer

Newton

Answer

Pascal

Question 4

An example of an isobaric process is:

Accepted Answer

Evaporation of water at constant temperature

Answer

Adiabatic compression of a gas

Answer

Isochoric heating of a solid

Answer

Isothermal expansion of a gas

Question 5

A reversible process is one that:

Accepted Answer

Can be reversed without any change in the system or surroundings

Answer

Can be reversed with a change in the system but no change in the surroundings

Answer

Can be reversed with a change in the surroundings but no change in the system

Answer

Cannot be reversed

Question 6

The entropy change of a system that absorbs 100 J of heat at a temperature of 273 K is:

Accepted Answer

0.36 J/K

Answer

100 J/K

Answer

273 J/K

Answer

1000 J/K

Question 7

Which of the following is the SI unit of entropy?

Accepted Answer

Joule per Kelvin (J/K)

Answer

Kelvin per Joule (K/J)

Answer

Watt per Kelvin (W/K)

Answer

Horsepower per Kelvin (hp/K)

Question 8

The first law of thermodynamics affirms that?

Accepted Answer

Energy cannot be created or destroyed, only transferred or transformed.

Answer

Heat is always transferred from a higher temperature to a lower temperature.

Answer

The entropy of an isolated system always increases.

Answer

The efficiency of a heat engine can never exceed 100%.

Question 9

Which of the following processes is considered reversible?

Accepted Answer

Expansion of an ideal gas into a vacuum

Answer

Heat transfer through a finite temperature difference

Answer

Mixing of two gases at different temperatures

Answer

Friction between two surfaces

Question 10

The efficiency of a Carnot heat engine that operates between two reservoirs at temperatures T1 and T2 is described by:

Accepted Answer

T1 - T2 / T1

Answer

T1 + T2 / T1

Answer

T2 - T1 / T2

Answer

T2 + T1 / T2

Question 11

The enthalpy of a system is defined as:

Accepted Answer

Internal energy plus the product of pressure and volume

Answer

Internal energy minus the product of pressure and volume

Answer

Pressure plus the product of temperature and volume

Answer

Temperature plus the product of pressure and volume

Question 12

The second law of thermodynamics implies:

Accepted Answer

It is a statement about the direction of time.

Answer

It allows for the existence of perpetual motion machines.

Answer

It is a consequence of the conservation of energy.

Answer

It is only applicable to open systems.

Question 13

The critical point of a substance is the point at which:

Accepted Answer

The liquid and gas phases are indistinguishable

Answer

The solid and liquid phases are indistinguishable

Answer

The gas and solid phases are indistinguishable

Answer

The triple point of the substance occurs

Question 14

In an adiabatic process, how does the first law of thermodynamics apply?

Accepted Answer

The change in internal energy equals the work done on the system.

Answer

Heat is transferred into the system.

Answer

The temperature of the system always increases.

Answer

The entropy of the system always decreases.

Question 15

How does the direction of heat transfer affect the entropy of a system?

Accepted Answer

Entropy increases when heat transfers from a hot to a cold reservoir.

Answer

Entropy decreases when heat transfers from a hot to a cold reservoir.

Answer

Heat transfer has no effect on entropy.

Question 16

Define isentropic processes and explain their significance in engineering systems. Provide specific examples to illustrate your explanation.

Accepted Answer

Isentropic processes are thermodynamic processes that occur without heat transfer to or from the system, resulting in constant entropy.

Answer

Isentropic processes involve heat transfer but experience no change in entropy.

Answer

Isentropic processes occur with an increase in entropy.

Answer

Isentropic processes have no practical implications in engineering systems.

Question 17

Which of the following is NOT a fundamental law of thermodynamics?

Accepted Answer

Entropy law

Answer

Zeroth law

Answer

First law

Answer

Second law

Question 18

In an isothermal process, which thermodynamic property remains constant?

Accepted Answer

Temperature

Answer

Pressure

Answer

Volume

Answer

Internal energy

Question 19

An ideal gas undergoes an adiabatic compression. Which of the following accurately describes the change in its temperature?

Accepted Answer

Increases

Answer

Decreases

Answer

Remains unchanged

Answer

Cannot be determined without additional information

Question 20

The efficiency of a heat engine is defined as:

Accepted Answer

Work output over heat input

Answer

Heat input over work output

Answer

Change in internal energy over heat input

Answer

Change in internal energy over work output

Question 21

The thermal conductivity of a material is a measure of its ability to:

Accepted Answer

Transfer heat flow

Answer

Resist heat flow

Answer

Store heat

Answer

Generate heat

Question 22

Which of the following is NOT a mode of heat transfer?

Accepted Answer

Diffusion

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 23

The Stefan-Boltzmann constant is used to calculate:

Accepted Answer

Heat transfer by radiation

Answer

Heat transfer by conduction

Answer

Heat transfer by convection

Answer

Heat capacity

Question 24

According to the first law of thermodynamics, energy:

Accepted Answer

Cannot be created or destroyed within an isolated system

Answer

Is only conserved in reversible processes

Answer

Is lost as heat in any process

Answer

Is always converted to mechanical work

Question 25

Which of the following processes occurs at constant temperature?

Accepted Answer

Isothermal

Answer

Isentropic

Answer

Adiabatic

Answer

Isochoric

Question 26

The SI unit of entropy is:

Accepted Answer

Joule per Kelvin (J/K)

Answer

Joule (J)

Answer

Kelvin per Joule (K/J)

Answer

Kelvin (K)

Question 27

A common application of thermodynamics in engineering is:

Accepted Answer

Design and optimization of heat engines

Answer

Astrophysics

Answer

Literary analysis

Answer

Economics

Question 28

In a refrigeration system, the function of the condenser is to:

Accepted Answer

Release heat to the surroundings

Answer

Compress the refrigerant

Answer

Absorb heat from the surroundings

Answer

Expand the refrigerant

Question 29

Which of the following is NOT a thermodynamic property?

Accepted Answer

Velocity

Answer

Volume

Answer

Pressure

Answer

Temperature

Question 30

Which of the following is the first law of thermodynamics?

Accepted Answer

Energy cannot be created or destroyed, but it can be transferred or transformed.

Answer

Energy can be destroyed but not created.

Answer

Energy can be created but not destroyed.

Question 31

In an isobaric process involving an ideal gas, as the temperature of the gas is increased, what happens to its volume?

Accepted Answer

Increases

Answer

Decreases

Answer

Varies unpredictably

Answer

Stays the same

Question 32

Which of the thermodynamic systems is characterized by a moving boundary allowing the exchange of matter and energy with its surroundings?

Accepted Answer

A piston-cylinder system with a moving piston

Answer

A sealed can of gas

Answer

A refrigerator

Answer

A closed flask containing water

Question 33

Entropy is a measure of what physical property?

Accepted Answer

Disorder or randomness of a system

Answer

Pressure

Answer

Temperature

Question 34

Heat transfer occurs according to what fundamental principle?

Accepted Answer

From higher temperatures to lower temperatures

Answer

Randomly and unpredictably

Answer

From lower temperatures to higher temperatures

Question 35

Which property characterizes an ideal gas?

Accepted Answer

The product of pressure and volume is proportional to temperature.

Answer

The density is constant.

Answer

The specific heat capacity is zero.

Question 36

What is the significance of the critical point on a phase diagram?

Accepted Answer

It represents the highest temperature and pressure where a substance can coexist in liquid and gas phases.

Answer

It indicates the melting point of the substance.

Question 37

In the context of engineering systems, what is a common application of thermodynamics?

Accepted Answer

Design of heat engines and refrigerators

Answer

Prediction of weather patterns

Answer

Control of biological processes

Answer

Analysis of chemical reactions

Question 38

Describe the distinction between heat and internal energy.

Accepted Answer

Heat is energy transferred due to a temperature difference, while internal energy is the total energy within a system.

Answer

Heat is a form of internal energy.

Question 39

What is the triple point in a phase diagram?

Accepted Answer

The point where the solid, liquid, and gas phases coexist in equilibrium.

Answer

The point where the solid and liquid phases become indistinguishable.

Answer

The point where the liquid and gas phases become indistinguishable.

Question 40

Which property is NOT characteristic of an ideal gas?

Accepted Answer

Viscosity

Answer

Temperature

Answer

Pressure

Answer

Volume

Question 41

According to the first law of thermodynamics, what happens to energy?

Accepted Answer

It can be neither created nor destroyed, only transferred or transformed.

Answer

It spontaneously decreases over time.

Answer

It can be converted into matter.

Question 42

Which process listed below is irreversible?

Accepted Answer

Friction

Answer

Isochoric heating

Answer

Adiabatic compression

Answer

Isothermal expansion

Question 43

Entropy refers to which aspect of a system?

Accepted Answer

Its degree of disorder or randomness.

Answer

Its thermal conductivity.

Answer

Its specific heat capacity.

Answer

Its potential energy.

Question 44

Which factor does NOT influence the rate of heat transfer?

Accepted Answer

Pressure

Answer

Temperature difference

Answer

Conductivity of the medium

Answer

Surface area

Question 45

What is the primary purpose of a heat exchanger?

Accepted Answer

To facilitate heat exchange between two fluids.

Answer

To store thermal energy

Answer

To generate heat

Answer

To convert heat into electricity

Question 46

Which of the following is a type of thermodynamic system that permits mass and energy exchange with its surroundings?

Accepted Answer

Open system

Answer

Closed system

Answer

Adiabatic system

Answer

Isolated system