Work and Heat Transfer: Master Thermodynamics Concepts

Question 1

Which of the following is **not** a mode of work transfer?

Accepted Answer

Heat transfer

Answer

Mechanical work

Answer

Electrical work

Answer

Chemical work

Question 2

Identify the thermodynamic process during which both temperature and pressure remain constant.

Accepted Answer

Isothermal process

Answer

Adiabatic process

Answer

Isentropic process

Answer

Isochoric process

Question 3

According to the first law of thermodynamics, energy can be:

Accepted Answer

Transferred or converted

Answer

Created or destroyed

Answer

Stored or released

Answer

Lost or gained

Question 4

Define the efficiency of a heat engine.

Accepted Answer

Work output / Heat input

Answer

Heat input / Work output

Answer

(Work output - Heat input) / Heat input

Answer

Heat input / (Heat input - Work output)

Question 5

Which of the following describes the thermal conductivity of a material?

Accepted Answer

Ability to transfer heat

Answer

Dependence on temperature and phase

Answer

Same for all materials

Answer

Decreasing with increasing thickness

Question 6

Which of the following factors is most influential in determining the rate of heat transfer by conduction?

Accepted Answer

Thermal conductivity

Answer

Temperature gradient

Answer

Cross-sectional area

Answer

Fluid velocity

Question 7

The efficiency of a heat engine is measured as:

Accepted Answer

Work output per unit of heat input

Answer

Heat input per unit of work output

Answer

Heat rejected per unit of heat absorbed

Answer

Heat absorbed per unit of heat rejected

Question 8

Which of the following is NOT a typical application of heat transfer analysis in engineering?

Accepted Answer

Design of bridges

Answer

Design of heat exchangers

Answer

Thermal management of electronic devices

Answer

Analysis of internal combustion engines

Question 9

The rate of heat transfer by conduction through a slab is given by:

Accepted Answer

Q = k * A * (T1 - T2) / L

Answer

Q = h * A * (T1 - T2)

Answer

Q = ε * σ * A * (T1^4 - T2^4)

Answer

Q = m * c * (T1 - T2)

Question 10

Which type of fluid flow is characterized by random, irregular motion of fluid particles?

Accepted Answer

Turbulent flow

Answer

Laminar flow

Answer

Poiseuille flow

Answer

Couette flow

Question 11

The efficiency of a Carnot heat engine operating between two reservoirs at temperatures T1 and T2 is:

Accepted Answer

η = 1 - (T2 / T1)

Answer

η = (T1 - T2) / T1

Answer

η = (T2 - T1) / T1

Answer

η = 1 - (T1 / T2)

Question 12

Which of the following processes is adiabatic?

Accepted Answer

Adiabatic expansion

Answer

Isothermal compression

Answer

Isochoric heating

Answer

Isobaric cooling

Question 13

The entropy change of a system undergoing a reversible adiabatic process is:

Accepted Answer

ΔS = 0

Answer

ΔS > 0

Answer

ΔS < 0

Answer

Cannot be determined

Question 14

Which of the following is a type of thermodynamic system that can exchange both heat and work with its surroundings?

Accepted Answer

Open system

Answer

Closed system

Answer

Isolated system

Answer

Adiabatic system

Question 15

The enthalpy of a system is equal to:

Accepted Answer

U + PV

Answer

U - PV

Answer

PV - U

Answer

U / PV

Question 16

Which type of work involves a change in the system's volume?

Accepted Answer

Boundary work

Answer

Shaft work

Answer

Electrical work

Answer

Magnetic work

Question 17

The first law of thermodynamics states that:

Accepted Answer

Energy cannot be created or destroyed.

Answer

Entropy can never decrease.

Answer

Heat always flows from hot to cold.

Answer

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

Question 18

Radiation heat transfer occurs through:

Accepted Answer

Electromagnetic waves

Answer

Fluid motion

Answer

Direct contact

Answer

Mass diffusion

Question 19

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

Accepted Answer

Diffusion

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 20

Which of the following is a closed system in Thermodynamics?

Accepted Answer

A sealed bottle of water

Answer

A room with an open window

Answer

A car engine running at constant speed

Answer

A bicycle pump

Question 21

The first law of thermodynamics expresses the principle of:

Accepted Answer

Conservation of energy

Answer

Entropy increase

Answer

Irreversibility

Answer

Equilibrium

Question 22

Which of the following processes can be considered isothermal?

Accepted Answer

Expanding a gas with no heat transfer

Answer

Heating a gas in a sealed container

Answer

Cooling a gas through a throttle valve

Answer

Compressing a gas adiabatically

Question 23

Entropy is a measure of a system's:

Accepted Answer

Disorder

Answer

Order

Answer

Energy

Answer

Volume

Question 24

A heat engine operates with an efficiency of 40%. If the work output is 100 kilojoules, what is the heat input to the engine?

Accepted Answer

150 kJ

Answer

60 kJ

Answer

100 kJ

Answer

250 kJ

Question 25

Which of the following correctly represents the mathematical form for calculating the work done by a system in thermodynamics?

Accepted Answer

δW = PdV

Answer

δQ = TdS

Answer

dU = TdS - PdV

Answer

dF = -SdT - PdV

Question 26

For any given material, the SI unit representing its thermal conductivity is:

Accepted Answer

W/(m·K)

Answer

kJ/(kg·K)

Answer

Jg/s

Answer

m²/s

Question 27

In conduction heat transfer through a material, the rate of heat flow is directly proportional to the:

Accepted Answer

Temperature gradient

Answer

Cross-sectional area

Answer

Thickness of the material

Answer

Specific heat capacity

Question 28

Which device is commonly used to measure the rate of heat transfer due to convection?

Accepted Answer

Heat flux sensor

Answer

Thermocouple

Answer

Anemometer

Answer

Calorimeter

Question 29

The emissivity of a surface primarily measures its ability to:

Accepted Answer

Emit radiation

Answer

Absorb radiation

Answer

Reflect radiation

Answer

Transmit radiation

Question 30

According to the first law of thermodynamics, which of the following statements is true?

Accepted Answer

Energy can neither be created nor destroyed, only transformed.

Answer

Entropy decreases in a closed system over time.

Answer

Heat flows from a colder to a hotter object.

Answer

A heat engine can have an efficiency exceeding 100%.

Question 31

In a closed system experiencing an adiabatic change, what remains constant?

Accepted Answer

Entropy

Answer

Temperature

Answer

Volume

Answer

Pressure

Question 32

In a reversible heat engine operating in a cycle, what is the net work output over the complete cycle?

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Depends on the cycle

Question 33

Which of the following processes is isobaric?

Accepted Answer

Constant pressure

Answer

Constant volume

Answer

Constant temperature

Answer

Adiabatic

Question 34

In a system undergoing a cyclical process, what is the net change in internal energy over the complete cycle?

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Depends on the cycle

Question 35

The mathematical formula representing the rate of heat transfer by conduction is:

Accepted Answer

Fourier's law

Answer

Newton's law of cooling

Answer

Stefan-Boltzmann law

Answer

Wien's displacement law

Question 36

The efficiency of a heat engine is defined as:

Accepted Answer

Work output of the engine / Heat input to the engine

Answer

Heat input to the engine / Work output of the engine

Answer

Change in internal energy / Heat input to the engine

Answer

Heat rejected / Work output of the engine

Question 37

Which gas among the following is NOT a greenhouse gas?

Accepted Answer

Nitrogen

Answer

Carbon dioxide

Answer

Methane

Answer

Water vapor

Question 38

Which of the following processes does NOT involve heat transfer?

Accepted Answer

Adiabatic compression

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 39

Which of the following factors does NOT influence the rate of heat conduction?

Accepted Answer

Fluid velocity

Answer

Temperature gradient

Answer

Material thermal conductivity

Answer

Cross-sectional area

Question 40

What is the fundamental significance of the entropy principle?

Accepted Answer

It determines the direction of spontaneous processes.

Answer

It provides a measure of thermal energy in a system.

Answer

It relates heat transfer to work done.

Answer

It explains the behaviour of ideal gases under all conditions.

Question 41

Which statement best represents the Clausius statement of the second law of thermodynamics?

Accepted Answer

Heat cannot flow spontaneously from a cold body to a hotter body.

Answer

The entropy of an isolated system decreases over time.

Answer

Every spontaneous process results in an increase in free energy.

Answer

The efficiency of a heat engine can be greater than 100%.

Question 42

What is the primary purpose of a condenser in a vapour-compression refrigeration cycle?

Accepted Answer

To remove heat from the refrigerant

Answer

To increase the pressure of the refrigerant

Answer

To cool the compressor

Answer

To expand the refrigerant

Question 43

Which of the following is a fundamental assumption of the ideal gas law?

Accepted Answer

Negligible intermolecular forces between gas particles

Answer

Constant specific heat capacities over a wide temperature range

Answer

Uniform pressure and temperature distribution throughout the gas

Answer

Gas particles do not undergo phase transitions under any conditions

Question 44

Which of the following is an example of an adiabatic process?

Accepted Answer

Expansion of a gas in a vacuum

Answer

Compression of a gas in a cylinder

Answer

Condensation of a vapour

Answer

Evaporation of a liquid

Question 45

The specific heat capacity of a substance is defined as:

Accepted Answer

The amount of heat required to raise the temperature of 1 kg of the substance by 1 K

Answer

The amount of heat required to raise the temperature of 1 g of the substance by 1 K

Answer

The amount of heat required to raise the temperature of 1 mole of the substance by 1 K

Answer

The amount of heat required to raise the temperature of 1 m³ of the substance by 1 K

Question 46

Explain the fundamental difference between reversible and irreversible heat transfer processes.

Accepted Answer

Reversible processes can be reversed without any loss of energy, while irreversible processes cannot.

Answer

Irreversible processes are more efficient than reversible processes.

Answer

Reversible processes only occur in isolated systems, while irreversible processes occur in open systems.

Answer

There is no distinction between reversible and irreversible heat transfer.

Question 47

Provide the mathematical equation that defines thermal conductivity.

Accepted Answer

k = Q / (A*t*(dT/dx))

Answer

k = Q / (A*t*(dT/dy))

Answer

k = Q / (A*t*(dT/dz))

Answer

k = (dT/dx) / (Q/(A*t))

Question 48

Explain the significance of heat capacity in thermodynamics.

Accepted Answer

It determines the amount of heat required to raise the temperature of a substance by a specific amount.

Answer

It determines the rate at which heat flows through a material.

Answer

It is directly proportional to the thermal conductivity of a material.

Answer

It has no significant relevance in thermodynamics.

Question 49

Identify the process that is considered isentropic.

Accepted Answer

Adiabatic expansion of an ideal gas

Answer

Isothermal compression of a gas

Answer

Irreversible heat transfer

Answer

Adiabatic compression of a real gas

Question 50

Define a thermodynamic system.

Accepted Answer

A specified quantity of matter or region of space that is being studied.

Answer

A device that converts heat into work.

Answer

A process that involves a change in temperature.

Answer

A substance that has a high thermal conductivity.

Question 51

Identify the primary characteristic of heat transfer by conduction.

Accepted Answer

Requires a temperature difference

Answer

Involves the movement of matter

Answer

Occurs independently of the material's properties

Answer

Is unaffected by the surface area

Question 52

A reversible process is one that:

Accepted Answer

Can be reversed without any change in the system or surroundings

Answer

Occurs spontaneously

Answer

Releases heat into the surroundings

Answer

Absorbs heat from the surroundings

Question 53

What is the SI unit of thermal conductivity?

Accepted Answer

W/(m·K)

Answer

J/(kg·°C)

Answer

cal/(s·cm·°C)

Answer

BTU/(hr·ft·°F)

Question 54

Which of the following processes involves the conversion of thermal energy into mechanical energy?

Accepted Answer

Heat engine

Answer

Refrigerator

Answer

Heat pump

Answer

Power plant

Question 55

What is the mathematical representation of the efficiency of a heat engine?

Accepted Answer

η = (Qh - Qc) / Qh

Answer

η = (Qc - Qh) / Qc

Answer

η = W / Qh

Answer

η = Qc / W

Question 56

The rate of heat transfer by conduction through a plane wall is given by which equation?

Accepted Answer

Q = kA(T1 - T2)/x

Answer

Q = hA(T1 - T2)

Answer

Q = σA(T1^4 - T2^4)

Answer

Q = mcp(T2 - T1)

Question 57

Which of the following is the unit of thermal conductivity?

Accepted Answer

W/(m·K)

Answer

J/(kg·K)

Answer

kcal/(h·m·°C)

Answer

Btu/(ft·h·°F)

Question 58

What is the effect of increasing the surface area on the rate of heat transfer by convection?

Accepted Answer

It increases the rate of heat transfer

Answer

It decreases the rate of heat transfer

Answer

It has no effect on the rate of heat transfer

Answer

It depends on the fluid velocity and temperature difference

Question 59

What is the fundamental difference between heat and work?

Accepted Answer

Heat is a form of energy transfer, while work is a force applied over a distance.

Answer

Work is a form of energy transfer, while heat is a force applied over a distance.

Answer

Heat and work are the same thing.

Answer

Heat and work are both forms of energy, but they cannot be transferred.

Question 60

What is the first law of thermodynamics?

Accepted Answer

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

Answer

The total entropy of an isolated system always increases over time.

Answer

Heat flows from hot to cold.

Answer

The pressure of a gas is inversely proportional to its volume.