Question 1

The entropy of a system remains constant during an adiabatic change even if the change is irreversible.

Accepted Answer

A) True 
 B)False

Question 2

Which of the following is a statement of the third law of thermodynamics?

Accepted Answer

A)  If two objects are in equilibrium with a third, then they are in thermal equilibrium with one another. 
B)  The entropy of the universe cannot decrease. 
C)  The entropy of the universe cannot increase. 
D)  All reversible engines operating between the same two temperatures have the same efficiency. 
E)  It is impossible to lower the temperature of an object to absolute zero in a finite number of steps. 
A)  If two objects are in equilibrium with a third, then they are in thermal equilibrium with one another. 
B)  The entropy of the universe cannot decrease. 
C)  The entropy of the universe cannot increase. 
D)  All reversible engines operating between the same two temperatures have the same efficiency. 
E)  It is impossible to lower the temperature of an object to absolute zero in a finite number of steps.

Question 3

An athlete doing push-ups performs 650 kJ of work and loses 425 kJ of heat. What is the change in the internal energy of the athlete?

Accepted Answer

A)  -225 kJ 
B)  -1075 kJ 
C)  1075 kJ 
D)  225 kJ 
E)  276 kJ 
A)  -225 kJ 
B)  -1075 kJ 
C)  1075 kJ 
D)  225 kJ 
E)  276 kJ

Question 4

A certain ideal gas has a value of γ = 4/3. What is its molar specific heat at constant pressure?

Accepted Answer

A)  5R/2 
B)  2R 
C)  3R 
D)  7R/2 
E)  4R 
A)  5R/2 
B)  2R 
C)  3R 
D)  7R/2 
E)  4R

Question 5

A monatomic ideal gas is compressed adiabatically to one-third of its initial volume. The resulting pressure will be

Accepted Answer

A)  three times as large as the initial value. 
B)  less than three times as large as the initial value. 
C)  more than three times as large as the initial value. 
D)  equal to the initial value. 
E)  impossible to predict on the basis of this data. 
A)  three times as large as the initial value. 
B)  less than three times as large as the initial value. 
C)  more than three times as large as the initial value. 
D)  equal to the initial value. 
E)  impossible to predict on the basis of this data.

Question 6

FIGURE 18-1  
-An ideal monatomic gas undergoes the reversible expansion shown in Figure 18-1, where V2 = 5V1 and P2 = 3P1. What is the change in internal energy of the gas in this process, in terms of the initial pressure and volume?

Accepted Answer

A)  7 P1V1 
B)  14 P1V1 
C)  21 P1V1 
D)  15 P1V1 
E)  29 P1V1 
A)  7 P1V1 
B)  14 P1V1 
C)  21 P1V1 
D)  15 P1V1 
E)  29 P1V1

Question 7

If a system undergoes a reversible process,

Accepted Answer

A)  it must be possible to restore the system to its original state. 
B)  it must be possible to restore the surroundings to their original state. 
C)  it must be possible to restore both the system and the surroundings to their original states. 
D)  it is impossible to restore either the the system or the surroundings to their original states. 
E)  the system must not interact with its surroundings. 
A)  it must be possible to restore the system to its original state. 
B)  it must be possible to restore the surroundings to their original state. 
C)  it must be possible to restore both the system and the surroundings to their original states. 
D)  it is impossible to restore either the the system or the surroundings to their original states. 
E)  the system must not interact with its surroundings.

Question 8

Two identical samples of a monatomic gas are initially at pressure P and occupy volume V. You perform two experiments which will both lead to the gas samples being compressed to final volumes one-third as large as their initial volumes. In one of the experiments you make the gas undergo an isothermal compression. In the second you make the gas undergo an adiabatic compression. It is correct to say that:

Accepted Answer

A)  The isothermal compression leads to a higher final pressure than the adiabatic compression and the gas exchanges heat with its surroundings. 
B)  The adiabatic compression leads to a higher final pressure than the isothermal compression and the gas does not exchange heat with its surroundings. 
C)  The isothermal compression leads to a lower final pressure than the isothermal compression and the gas does not exchange heat with its surroundings. 
D)  The adiabatic compression leads to a lower final pressure than the isothermal compression and the gas exchanges heat with its surroundings. 
E)  It is impossible to predict on the basis of this data. 
A)  The isothermal compression leads to a higher final pressure than the adiabatic compression and the gas exchanges heat with its surroundings. 
B)  The adiabatic compression leads to a higher final pressure than the isothermal compression and the gas does not exchange heat with its surroundings. 
C)  The isothermal compression leads to a lower final pressure than the isothermal compression and the gas does not exchange heat with its surroundings. 
D)  The adiabatic compression leads to a lower final pressure than the isothermal compression and the gas exchanges heat with its surroundings. 
E)  It is impossible to predict on the basis of this data.

Question 9

An inventor tries to sell you his new engine which takes in 40. Joules of heat at 87°C on each cycle, expels 30. Joules at 27°C, and does 10. Joules of work. Why are you not fooled, and can have him prosecuted as a fraud?

Accepted Answer

The greatest efficiency possib

Question 10

A reversible engine takes in 555. Joules per second and exhausts 482. watts.
(a) How much power does it produce?
(b) What is its efficiency?
(c) If operated in reverse as a refrigerator, what would be its COP?

Accepted Answer

(a)73.watt

Question 11

In the first law of thermodynamics, Q is the heat gained by the system, that is, Q is positive if the system gains heat.

Accepted Answer

A) True 
 B)False

Question 12

Internal energy is a state function.

Accepted Answer

A) True 
 B)False

Question 13

3.0 moles of gas expand from an initial volume of 0.040 m3 to a final volume of 0.085 m3 while the temperature of the gas is kept fixed at 300 K. How much work is done by the system?

Accepted Answer

A)  5.6 kJ 
B)  6.6 kJ 
C)  7.6 kJ 
D)  8.6 kJ 
E)  14 kJ 
A)  5.6 kJ 
B)  6.6 kJ 
C)  7.6 kJ 
D)  8.6 kJ 
E)  14 kJ

Question 14

For an ideal monatomic gas,

Accepted Answer

A)  Cp = Cv. 
B)  Cp > Cv. 
C)  Cp v. 
D)  More information is needed to answer this question. 
A)  Cp = Cv. 
B)  Cp > Cv. 
C)  Cp v. 
D)  More information is needed to answer this question.

Question 15

A 40.0-L container is divided into two equal parts by a rubber membrane. One half of the container has 1.80 moles of an ideal monatomic gas at 270 K, and the other half is a vacuum. The container does not allow any gas to escape but is free to exchange heat with the surroundings. The membrane breaks, the gas expands isothermally and eventually the gas reaches a new equilibrium condition occupying the entire volume. What is the change in entropy of the gas?

Accepted Answer

A)  10.4 J/K 
B)  9.16 J/K 
C)  12.5 J/K 
D)  14.3 J/K 
E)  16.4 J/K 
A)  10.4 J/K 
B)  9.16 J/K 
C)  12.5 J/K 
D)  14.3 J/K 
E)  16.4 J/K

Question 16

A heat engine absorbs 64 kcal of heat each cycle and exhausts 42 kcal.
(a) Calculate the efficiency each cycle.
(b) Calculate the work done each cycle.

Accepted Answer

The answer of A heat engine absorbs 64 kcal of...

Question 17

An ideal monatomic gas undergoes a reversible expansion to 1.5 times its original volume. In which of these processes does the gas perform the least amount of work?

Accepted Answer

A)  at constant pressure 
B)  if the pressure increases in proportion to the volume 
C)  if the pressure decreases in proportion to the volume 
D)  at constant temperature 
E)  adiabatically 
A)  at constant pressure 
B)  if the pressure increases in proportion to the volume 
C)  if the pressure decreases in proportion to the volume 
D)  at constant temperature 
E)  adiabatically

Exam 18: The Laws of Thermodynamics

The entropy of a system remains constant during an adiabatic change even if the change is irreversible.

Which of the following is a statement of the third law of thermodynamics?

An athlete doing push-ups performs 650 kJ of work and loses 425 kJ of heat. What is the change in the internal energy of the athlete?

A certain ideal gas has a value of γ = 4/3. What is its molar specific heat at constant pressure?

A monatomic ideal gas is compressed adiabatically to one-third of its initial volume. The resulting pressure will be

FIGURE 18-1 -An ideal monatomic gas undergoes the reversible expansion shown in Figure 18-1, where V2 = 5V1 and P2 = 3P1. What is the change in internal energy of the gas in this process, in terms of the initial pressure and volume?

If a system undergoes a reversible process,

An inventor tries to sell you his new engine which takes in 40. Joules of heat at 87°C on each cycle, expels 30. Joules at 27°C, and does 10. Joules of work. Why are you not fooled, and can have him prosecuted as a fraud?

A reversible engine takes in 555. Joules per second and exhausts 482. watts. (a) How much power does it produce? (b) What is its efficiency? (c) If operated in reverse as a refrigerator, what would be its COP?

In the first law of thermodynamics, Q is the heat gained by the system, that is, Q is positive if the system gains heat.

Internal energy is a state function.

3.0 moles of gas expand from an initial volume of 0.040 m3 to a final volume of 0.085 m3 while the temperature of the gas is kept fixed at 300 K. How much work is done by the system?

For an ideal monatomic gas,

A heat engine absorbs 64 kcal of heat each cycle and exhausts 42 kcal. (a) Calculate the efficiency each cycle. (b) Calculate the work done each cycle.

An ideal monatomic gas undergoes a reversible expansion to 1.5 times its original volume. In which of these processes does the gas perform the least amount of work?

Introduction to Physics

One-Dimensional Kinematics

Vectors in Physics

Two-Dimensional Kinematics

Newtons Laws of Motion

Applications of Newtons Laws

Work and Kinetic Energy

Potential Energy and Conservation of Energy

Linear Momentum and Collisions

Rotational Kinematics and Energy

Rotational Dynamics and Static Equilibrium

Gravity

Oscillations About Equilibrium

Waves and Sound

Fluids

Temperature and Heat

Phases and Phase Changes

Electric Charges, Forces, and Fields

Electric Potential and Electric Potential Energy

Electric Current and Direct-Current Circuits

Magnetism

Magnetic Flux and Faradays Law of Induction

Alternating-Current Circuits

Electromagnetic Waves

Geometrical Optics

Optical Instruments

Physical Optics: Interference and Diffraction

Relativity

Quantum Physics

Atomic Physics

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FIGURE 18-1 -An ideal monatomic gas undergoes the reversible expansion shown in Figure 18-1, where V₂ = 5V₁ and P₂ = 3P₁. What is the change in internal energy of the gas in this process, in terms of the initial pressure and volume?

3.0 moles of gas expand from an initial volume of 0.040 m³ to a final volume of 0.085 m³ while the temperature of the gas is kept fixed at 300 K. How much work is done by the system?