Applications of the First Law of Thermodynamics: Online Learning Quizzes

Question 1

Which of the following is NOT an application of the First Law of Thermodynamics in engineering systems?

Accepted Answer

Predicting weather patterns

Answer

Designing efficient heat engines

Answer

Analyzing refrigeration systems

Answer

Evaluating power plant efficiency

Question 2

Which of the following is NOT an assumption of the First Law of Thermodynamics?

Accepted Answer

Energy can be created or destroyed.

Answer

Energy can be transferred from one form to another.

Answer

The total energy of an isolated system remains constant.

Answer

Heat is a form of energy that can be transferred between systems.

Question 3

A heat exchanger is used to transfer heat between two fluids. The effectiveness of a heat exchanger is defined as the ratio of the actual heat transfer rate to the:

Accepted Answer

Maximum possible heat transfer rate

Answer

Minimum possible heat transfer rate

Answer

Average heat transfer rate

Answer

Design heat transfer rate

Question 4

Which of the following is a measure of the ability of a system to store thermal energy?

Accepted Answer

Specific heat capacity

Answer

Latent heat

Answer

Thermal conductivity

Answer

Emissivity

Question 5

The enthalpy of a system is defined as:

Accepted Answer

The sum of the internal energy and the product of pressure and volume

Answer

The difference between the internal energy and the product of pressure and volume

Answer

The ratio of the internal energy to the volume

Answer

The product of the pressure and the volume

Question 6

The entropy of a system is a measure of:

Accepted Answer

The randomness or disorder of the system

Answer

The energy of the system

Answer

The temperature of the system

Answer

The volume of the system

Question 7

Which of the following is NOT a consequence of the Second Law of Thermodynamics?

Accepted Answer

All natural processes are reversible.

Answer

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

Answer

Entropy always increases in an isolated system.

Answer

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

Question 8

Which of the following processes is **not** an example of the practical application of the First Law of Thermodynamics?

Accepted Answer

Analysis of photovoltaic cells

Answer

Operation of heat engines

Answer

Design of refrigeration systems

Answer

Evaluation of fuel cell efficiency

Question 9

In a heat engine operating according to the First Law of Thermodynamics, what is the relationship between the heat added (Q_in) and the net work done (W_out)?

Accepted Answer

Q_in can be greater than, equal to, or less than W_out, depending on the efficiency of the engine

Answer

Q_in is always greater than W_out

Answer

Q_in is always equal to W_out

Answer

Q_in is always less than W_out

Question 10

Which thermodynamic cycle is commonly used in refrigeration systems?

Accepted Answer

Carnot cycle

Answer

Rankine cycle

Answer

Otto cycle

Answer

Brayton cycle

Question 11

According to the Carnot theorem, what is the maximum efficiency (η) of a heat engine operating between two reservoirs at absolute temperatures T_1 and T_2?

Accepted Answer

η = (T_1 - T_2) / T_1

Answer

η = 100%

Answer

η = T_1 / T_2

Answer

η = (T_2 - T_1) / T_1

Question 12

In a closed system, according to the principle of conservation of entropy, what is the total change in entropy over time?

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Unpredictable

Question 13

Which of the following is a thermodynamic property?

Accepted Answer

Temperature

Answer

Mass

Answer

Velocity

Answer

Acceleration

Question 14

When the volume of a system decreases during a process, what is the sign of the work done by the system?

Accepted Answer

Negative

Answer

Positive

Answer

Zero

Answer

Depends on the specific process

Question 15

An ideal heat engine operates between a high-temperature reservoir at 1000 K and a low-temperature reservoir at 300 K. What happens to the entropy of the high-temperature reservoir?

Accepted Answer

It decreases.

Answer

It increases.

Answer

It stays the same.

Question 16

Which of the following is a limitation of the Second Law of Thermodynamics?

Accepted Answer

It cannot predict the direction of spontaneous processes in systems that are not closed.

Answer

It assumes that all processes are reversible.

Answer

It does not account for the role of entropy.

Answer

It is only applicable to systems in equilibrium.

Question 17

A gas turbine operates on a Brayton cycle. Which of the following is the correct sequence of processes in the cycle?

Accepted Answer

Adiabatic compression, constant pressure heat addition, adiabatic expansion, constant volume heat rejection

Answer

Adiabatic expansion, constant volume heat addition, adiabatic compression, constant pressure heat rejection

Answer

Constant pressure heat addition, adiabatic expansion, adiabatic compression, constant volume heat rejection

Answer

Constant volume heat addition, adiabatic expansion, adiabatic compression, constant pressure heat rejection

Question 18

Which of the following is NOT an application of the First Law of Thermodynamics in engineering systems?

Accepted Answer

Derivation of the Second Law of Thermodynamics

Answer

Analysis of heat engines

Answer

Design of refrigerators

Answer

Thermodynamic optimization of power plants

Question 19

In a heat engine, the heat absorbed from the high-temperature reservoir is:

Accepted Answer

Greater than or equal to the work done by the engine

Answer

Exactly equal to the work done by the engine

Answer

Less than or equal to the work done by the engine

Answer

Equal to the heat rejected to the low-temperature reservoir

Question 20

Latent heat of fusion is the:

Accepted Answer

Heat required to melt a unit mass of a substance at its melting point

Answer

Heat released when a unit mass of a substance freezes at its freezing point

Answer

Heat required to vaporize a unit mass of a substance at its boiling point

Answer

Heat released when a unit mass of a substance condenses at its boiling point

Question 21

Which of the following is the ideal cycle for a heat pump?

Accepted Answer

Carnot cycle

Answer

Rankine cycle

Answer

Otto cycle

Answer

Diesel cycle

Question 22

Which of the following systems contradicts the First Law of Thermodynamics?

Accepted Answer

Perpetual motion machine

Answer

Refrigerator

Answer

Heat engine

Answer

Steam turbine

Question 23

The enthalpy change of a reaction at constant pressure is equal to:

Accepted Answer

Heat absorbed by the system

Answer

Work done by the system

Answer

Heat released by the system

Answer

Entropy change multiplied by temperature

Question 24

In an isolated system, according to the Second Law of Thermodynamics, what happens to entropy?

Accepted Answer

Increases

Answer

Decreases

Answer

Stays the same

Question 25

A refrigerator maintains a cold reservoir at 270 K and a hot reservoir at 300 K. If the refrigerator extracts 1000 J of heat from the cold reservoir, what is the minimum amount of work required?

Accepted Answer

111.11 J

Answer

200 J

Answer

900 J

Answer

500 J

Question 26

A closed system undergoes a process where 500 J of heat is added and 200 J of work is done on the system. What is the change in internal energy of the system?

Accepted Answer

300 J

Answer

-700 J

Answer

-300 J

Answer

700 J

Question 27

A 10 kg mass is lifted vertically through a height of 5 meters. What is the change in gravitational potential energy of the mass?

Accepted Answer

490 J

Answer

100 J

Answer

500 J

Answer

250 J

Question 28

A system undergoes a cyclic process. Which of the following statements is always true about the system in such a process?

Accepted Answer

The net change in internal energy is zero.

Answer

The work done by the system is equal to the change in internal energy.

Answer

The heat added to the system is equal to the work done by the system.

Question 29

A heat engine operates between a high-temperature reservoir at 800 K and a low-temperature reservoir at 300 K. Calculate the Carnot efficiency of this engine.

Accepted Answer

62.5%

Answer

100%

Answer

37.5%

Answer

50%

Question 30

A closed system undergoes a process where it receives 100 kJ of heat and performs 50 kJ of work. Determine the change in internal energy of the system.

Accepted Answer

50 kJ

Answer

-150 kJ

Answer

-50 kJ

Answer

150 kJ

Question 31

A cyclic process is performed on a system, resulting in a net work done of 100 kJ. If the net heat transfer during the cycle is 50 kJ, determine the change in internal energy of the system.

Accepted Answer

0 kJ

Answer

50 kJ

Answer

100 kJ

Answer

-50 kJ

Question 32

A reversible heat engine operates between a high-temperature reservoir at 1000 K and a low-temperature reservoir at 300 K. Calculate the maximum work obtainable from 1 kJ of heat input into the engine.

Accepted Answer

0.7 kJ

Answer

1 kJ

Answer

0.3 kJ

Answer

0.5 kJ

Question 33

Which of the following is NOT a direct application of the First Law of Thermodynamics?

Accepted Answer

Calculation of reaction rates

Answer

Analyzing heat engines

Answer

Evaluating thermodynamic cycles

Answer

Designing refrigerators

Question 34

In a heat engine, the heat absorbed from the high-temperature reservoir is partially converted into work. The remaining heat is:

Accepted Answer

Rejected to the low-temperature reservoir

Answer

Stored within the engine

Answer

Used to increase the engine's efficiency

Answer

Transferred to the surroundings

Question 35

Which of the following is a fundamental principle of the First Law of Thermodynamics?

Accepted Answer

Energy is conserved

Answer

All processes are reversible

Answer

Entropy always increases

Answer

Heat and work are equivalent forms of energy

Question 36

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

Accepted Answer

(T₁ - T₂) / T₁

Answer

T₂ / (T₁ - T₂)

Answer

T₁ / (T₁ - T₂)

Answer

(T₂ - T₁) / T₁

Question 37

A limitation of the First Law of Thermodynamics is that it:

Accepted Answer

Does not account for irreversibilities

Answer

Cannot predict the direction of spontaneous processes

Answer

Assumes constant specific heats

Answer

Only applies to closed systems

Question 38

The power output of a refrigerator is typically measured in:

Accepted Answer

Watts

Answer

Calories per hour

Answer

Joules

Question 39

The First Law of Thermodynamics can be used to calculate the:

Accepted Answer

Change in internal energy of a system

Answer

Rate of heat transfer

Answer

Efficiency of a chemical reaction

Answer

Entropy change of the surroundings

Question 40

Which of the following processes is considered isentropic?

Accepted Answer

Adiabatic reversible process

Answer

Isochoric irreversible process

Answer

Adiabatic irreversible process

Answer

Isothermal irreversible process