Work and Heat Transfer: Interactive Quizzes for Thermodynamics Students

Question 1

Which process primarily involves heat transfer due to a temperature difference between two regions?

Accepted Answer

Thermal conduction through a metal rod

Answer

Isothermal compression of an ideal gas

Answer

Irreversible adiabatic expansion of a gas

Answer

Friction between two sliding surfaces

Question 2

In steady-state, one-dimensional conduction, the heat flux (q) is:

Accepted Answer

Directly proportional to the temperature gradient

Answer

Inversely proportional to the thermal conductivity

Answer

Independent of the cross-sectional area

Answer

Zero

Question 3

The SI unit of work is the:

Accepted Answer

Joule (J)

Answer

Newton (N)

Answer

Pascal (Pa)

Answer

Watt (W)

Question 4

Which of the following is NOT a consequence of the second law of thermodynamics?

Accepted Answer

All real processes are reversible

Answer

Heat naturally flows from warmer to cooler regions

Answer

Entropy increases during irreversible processes

Answer

Perpetual motion machines are impossible

Question 5

What is the fundamental principle behind the Carnot cycle?

Accepted Answer

It represents the most efficient heat engine possible

Answer

It involves two isothermal and two adiabatic processes

Answer

It is completely reversible and has zero entropy generation

Answer

It is commonly used in practical power plants

Question 6

What is the significance of Gibbs free energy?

Accepted Answer

It determines the spontaneity of a process at constant temperature and pressure

Answer

It represents the maximum non-expansion work obtainable from a system

Answer

It is always negative for endothermic reactions

Answer

It is independent of temperature

Question 7

In conduction heat transfer, heat is transferred through molecules in:

Accepted Answer

Direct contact

Answer

Movement of fluids

Answer

Electromagnetic waves

Answer

Diffusion

Question 8

Thermal conductivity is measured in the SI units of:

Accepted Answer

W/mK

Answer

W/m

Answer

m/s

Answer

J/kgK

Question 9

Thermal radiation heat transfer is unaffected by:

Accepted Answer

Fluid velocity

Answer

Surface emissivity

Answer

Surface temperature

Answer

Surface area

Question 10

A thermodynamic closed system process is characterized by:

Accepted Answer

No mass transfer

Answer

No heat transfer

Answer

No work transfer

Answer

Constant volume

Question 11

During an isothermal process, the:

Accepted Answer

Temperature is constant

Answer

Volume is constant

Answer

Pressure is constant

Answer

Entropy is constant

Question 12

An adiabatic process is one in which:

Accepted Answer

No heat transfer occurs

Answer

No work is done

Answer

Temperature remains constant

Answer

Pressure remains constant

Question 13

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

Accepted Answer

Evaporation

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 14

For a closed system undergoing a cyclic thermodynamic process, the net work done is:

Accepted Answer

Always zero

Answer

Always positive

Answer

Always negative

Answer

Dependent on the path taken

Question 15

Thermal conductivity is a measure of a material's ability to:

Accepted Answer

Transfer heat

Answer

Store heat

Answer

Withstand deformation

Answer

Reflect light

Question 16

Which factor does NOT influence the rate of heat transfer by conduction?

Accepted Answer

Fluid pressure

Answer

Temperature difference

Answer

Cross-sectional area

Answer

Material thickness

Question 17

The efficiency of a heat engine is defined as the ratio of:

Accepted Answer

Work output to heat input

Answer

Heat output to work input

Answer

Work input to heat output

Answer

Heat input to work output

Question 18

Which of the following processes is considered reversible in thermodynamics?

Accepted Answer

Expansion of an ideal gas

Answer

Friction

Answer

Heat transfer through a temperature gradient

Answer

Combustion

Question 19

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 change the phase of 1 kg of the substance

Answer

The temperature at which the substance changes phase

Answer

The thermal conductivity of the substance

Question 20

The first law of thermodynamics can be expressed as:

Accepted Answer

dQ = dU + dW

Answer

dU = dQ - dW

Answer

dW = dQ - dU

Question 21

Which of the following is an example of a reversible heat engine?

Accepted Answer

Stirling engine

Answer

Otto cycle engine

Answer

Rankine cycle engine

Answer

Diesel cycle engine

Question 22

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

Accepted Answer

(T1 - T2)/T1

Answer

T2/(T1 - T2)

Answer

(T1 - T2)/(T2 - T1)

Answer

1 - (T1 - T2)/T2

Question 23

Which of the following is a psychrometric property?

Accepted Answer

Relative humidity

Answer

Density

Answer

Thermal conductivity

Answer

Specific heat

Question 24

The enthalpy of a system is:

Accepted Answer

A measure of its heat content

Answer

Equal to its internal energy

Answer

Independent of its temperature

Answer

Equal to its pressure

Question 25

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

Accepted Answer

Diffusion

Answer

Convection

Answer

Radiation

Answer

Conduction

Question 26

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

Accepted Answer

Diffusion

Answer

Convection

Answer

Radiation

Answer

Conduction

Question 27

The SI unit of heat is:

Accepted Answer

Joule

Answer

Kelvin

Answer

Watt

Answer

Celsius

Question 28

Identify the mechanism of heat transfer by direct contact:

Accepted Answer

Conduction

Answer

Convection

Answer

Radiation

Answer

Evaporation

Question 29

What is the mathematical equation that represents the first law of thermodynamics?

Accepted Answer

dQ = dU + dW

Answer

dU = dQ + dW

Answer

dW = dQ + dU

Answer

dQ = dW - dU

Question 30

Calculate the thermal conductivity of a material that allows 500 W of heat to pass through it. The material is 2 cm thick, has an area of 1 m^2, and a temperature difference of 100 K across it.

Accepted Answer

2.0 W/mK

Answer

0.5 W/mK

Answer

25.0 W/mK

Answer

500.0 W/mK

Question 31

Which of the following is not a type of heat exchanger?

Accepted Answer

Condenser

Answer

Shell and tube heat exchanger

Answer

Plate heat exchanger

Answer

Double pipe heat exchanger

Question 32

What does the entropy generation number signify in thermodynamics?

Accepted Answer

The irreversibility of a process

Answer

The amount of heat lost in a process

Answer

The efficiency of a heat engine

Answer

It has no physical significance

Question 33

In a gas turbine engine, what is the primary function of a regenerator?

Accepted Answer

To enhance the cycle's thermal efficiency

Answer

To reduce pressure drop in the turbine

Answer

To regulate exhaust temperature

Answer

To optimize the combustion process

Question 34

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

Accepted Answer

Work

Answer

Convection

Answer

Conduction

Answer

Radiation

Question 35

In which process does heat transfer occur primarily through the collision of molecules?

Accepted Answer

Conduction

Answer

Convection

Answer

Phase change

Answer

Radiation

Question 36

Which material has a high thermal conductivity, allowing it to conduct heat efficiently?

Accepted Answer

Metal

Answer

Plastic

Answer

Glass

Answer

Wood

Question 37

What is the SI unit of heat transfer rate?

Accepted Answer

Watt

Answer

Calorie

Answer

Kelvin

Answer

Joule

Question 38

In a reversible adiabatic process, the change in entropy is:

Accepted Answer

Zero

Answer

Indeterminate

Answer

Positive

Answer

Negative

Question 39

The rate of heat transfer by thermal radiation is proportional to the fourth power of:

Accepted Answer

Absolute temperature of the source

Answer

Emissivity of the source

Answer

Surface area of the source

Answer

Stefan-Boltzmann constant

Question 40

Consider an isothermal compression of 1 kg of air in a piston-cylinder device from an initial state of 200 kPa and 27°C to a final pressure of 400 kPa. Assuming air behaves as an ideal gas, calculate the work done **on** the air during this process.

Accepted Answer

-115 kJ

Answer

115 kJ

Answer

-230 kJ

Answer

230 kJ

Question 41

A closed system undergoes a cycle consisting of four processes. The total work done by the system during the cycle is 100 kJ. According to the first law of thermodynamics, which statement accurately describes the net heat transfer to the system during the cycle?

Accepted Answer

The net heat transfer to the system is also 100 kJ.

Answer

The net heat transfer to the system is -100 kJ.

Answer

The net heat transfer to the system is zero.

Question 42

A heat engine operates between a high-temperature reservoir at 800 K and a low-temperature reservoir at 300 K. Determine the maximum theoretical thermal efficiency of this heat engine.

Accepted Answer

62.5%

Answer

0%

Answer

100%

Answer

37.5%

Question 43

A heat pump with a COP of 3 is utilized to heat a house. If the heating demand of the house is 10 kW, calculate the power input required to operate the heat pump.

Accepted Answer

3.33 kW

Answer

30 kW

Answer

10 kW

Answer

1 kW

Question 44

Consider a rigid tank containing 2 kg of water initially at 100 kPa and 25°C. Heat is added to the water until its temperature reaches 100°C. Assuming negligible changes in kinetic and potential energy, determine the heat transfer **into** the water.

Accepted Answer

750 kJ

Answer

500 kJ

Answer

1000 kJ

Question 45

A steam turbine operates adiabatically, receiving steam at 4 MPa and 400°C. The steam exits the turbine at 100 kPa, and the mass flow rate is 10 kg/s. Assuming steam behaves as an ideal gas, determine the approximate power output of the turbine.

Accepted Answer

Approximately 7 MW

Answer

Approximately 1 MW

Answer

Approximately 14 MW

Answer

Approximately 3.5 MW

Question 46

Identify the incorrect statement regarding the concept of enthalpy:

Accepted Answer

Enthalpy represents the total energy of a system.

Answer

Enthalpy is a convenient property in analyzing energy transfer during flow processes.

Answer

The change in enthalpy signifies the heat transfer at constant pressure.

Answer

Enthalpy is a state function, dependent solely on the system's current state.

Question 47

Which characteristic defines a reversible process?

Accepted Answer

It can be reversed without any net change in the universe.

Answer

It always results in maximum work output.

Answer

It is always isothermal.

Question 48

Which process among the following is **not** reversible?

Accepted Answer

The expansion of a gas through a throttling valve.

Answer

The slow, isothermal expansion of an ideal gas.

Answer

The slow, isothermal compression of an ideal gas.

Answer

The reversible adiabatic expansion of an ideal gas.