Question 1

A heat engine produces a power output of 1.5 * 105 W when it receives 50.0 MJ of heat per minute. The efficiency of the engine is

Accepted Answer

A)  0.18. 
B)  0.30. 
C)  0.03. 
D)  0.003. 
A)  0.18. 
B)  0.30. 
C)  0.03. 
D)  0.003. A

Question 2

The change in entropy when 55 g of ice at 0°C melts (the heat of fusion is 3.34 * 105 J/kg) to water at 0°C is

Accepted Answer

A)  0 J/K. 
B)  67 J/K. 
C)  -67 J/K. 
D)  infinite. 
A)  0 J/K. 
B)  67 J/K. 
C)  -67 J/K. 
D)  infinite. B

Question 3

An ideal gas is heated in a closed container. The net work done on the system

Accepted Answer

A)  is zero. 
B)  is positive. 
C)  is negative. 
D)  depends on the gas in the container. 
A)  is zero. 
B)  is positive. 
C)  is negative. 
D)  depends on the gas in the container. A

Question 4

In an adiabatic expansion of an ideal gas, 150 J of work is performed on the surroundings. The heat added or removed from the gas is

Accepted Answer

A)  0 J. 
B)  150 J. 
C)  -150 J. 
D)  unknown; not enough information is given to answer the question. 
A)  0 J. 
B)  150 J. 
C)  -150 J. 
D)  unknown; not enough information is given to answer the question.

Question 5

A heat pump with a coefficient of performance of 10 used 50 kW of power. The heat delivered to the house is

Accepted Answer

A)  5 kW. 
B)  50 kW. 
C)  60 kW. 
D)  500 kW. 
A)  5 kW. 
B)  50 kW. 
C)  60 kW. 
D)  500 kW.

Question 6

In an adiabatic expansion of an ideal gas, 150 J of work is performed on the surroundings. The change in the internal energy of the gas is

Accepted Answer

A)  0 J. 
B)  150 J. 
C)  -150 J. 
D)  unknown; not enough information is given to answer the question. 
A)  0 J. 
B)  150 J. 
C)  -150 J. 
D)  unknown; not enough information is given to answer the question.

Question 7

During an adiabatic process

Accepted Answer

A)  Q is greater than zero. 
B)  Q is less than zero. 
C)  Q is equal to zero. 
D)  all of the above are possible. 
A)  Q is greater than zero. 
B)  Q is less than zero. 
C)  Q is equal to zero. 
D)  all of the above are possible.

Question 8

The coefficient of performance, CP, for a heat pump is defined as

Accepted Answer

A)  Q1/W. 
B)  W/Q1. 
C)  Q2/W. 
D)  W/Q2. 
A)  Q1/W. 
B)  W/Q1. 
C)  Q2/W. 
D)  W/Q2.

Question 9

During an isobaric (constant pressure) expansion, the volume of an ideal gas increases from 0.15 m3 to 0.35 m3. The pressure during the expansion is 150 kPa. The work done by the system is

Accepted Answer

A)  -30 kJ. 
B)  30 kJ. 
C)  750 kJ. 
D)  -750 kJ. 
A)  -30 kJ. 
B)  30 kJ. 
C)  750 kJ. 
D)  -750 kJ.

Question 10

During an isothermal process involving an ideal gas, 150 J of heat is removed from the system. The work done by the gas is

Accepted Answer

A)  0 J. 
B)  150 J. 
C)  -150 J. 
D)  unknown; not enough information is given to answer the question. 
A)  0 J. 
B)  150 J. 
C)  -150 J. 
D)  unknown; not enough information is given to answer the question.

Question 11

For each 150 Btu a heat engine absorbs, the system exhausts 64 Btu. The efficiency of the engine is

Accepted Answer

A)  0.43. 
B)  0.57. 
C)  1.3. 
D)  2.3. 
A)  0.43. 
B)  0.57. 
C)  1.3. 
D)  2.3.

Question 12

The efficiency of a Carnot cycle is 0.20 when operating with a hot reservoir of 93°C. If the temperature of the cold reservoir is maintained, the temperature of the hot reservoir necessary to double the efficiency is

Accepted Answer

A)  47°C. 
B)  186°C. 
C)  215°C. 
D)  488°C. 
A)  47°C. 
B)  186°C. 
C)  215°C. 
D)  488°C.

Question 13

The perpetual motion machine of the first kind is

Accepted Answer

A)  a device that extracts thermal energy from a heat source and converts it into mechanical energy. 
B)  a device that supplies endless output of work without input of fuel. 
C)  a Carnot engine. 
D)  none of the above. 
A)  a device that extracts thermal energy from a heat source and converts it into mechanical energy. 
B)  a device that supplies endless output of work without input of fuel. 
C)  a Carnot engine. 
D)  none of the above.

Question 14

Two Carnot cycles have the same efficiency. The first operates between Th = 200°C and Tc = 100°C and the second operates with a hot reservoir of Th = 400°C. The lower reservoir's temperature is

Accepted Answer

A)  200°C. 
B)  258°C. 
C)  315°C. 
D)  531°C. 
A)  200°C. 
B)  258°C. 
C)  315°C. 
D)  531°C.

Question 15

The graph here represents a p-V diagram where the x axis is the volume in units of 10-3 m3 and the y axis is the pressure in units of 105 N/m2. The work done by the gas as it contracts from (p2, V2) to (p1, V1) along the path indicated is

Accepted Answer

A)  30 kJ. 
B)  10 kJ 
C)  -30 kJ. 
D)  10 kJ. 
A)  30 kJ. 
B)  10 kJ 
C)  -30 kJ. 
D)  10 kJ.

Question 16

A container of 1.5 kg of water with a specific heat of 4186 J/(kg·°C) is heated from 25°C to 95°C. The change in the entropy of the water is

Accepted Answer

A)  1300 J/K. 
B)  21 J/K. 
C)  17 J/K. 
D)  4.0 J/K. 
A)  1300 J/K. 
B)  21 J/K. 
C)  17 J/K. 
D)  4.0 J/K.

Question 17

The graph here represents a p-V diagram where the x axis is the volume in units of 10-3 m3 and the y axis is the pressure in units of 105 N/m2. The work done by the gas as it expands from (p1, V1) to (p2, V2) along the path indicated is

Accepted Answer

A)  30 kJ. 
B)  10 kJ 
C)  -30 kJ. 
D)  10 kJ. 
A)  30 kJ. 
B)  10 kJ 
C)  -30 kJ. 
D)  10 kJ.

Question 18

During an adiabatic process the change in the temperature of the system is

Accepted Answer

A)  greater than zero. 
B)  less than zero. 
C)  equal to zero. 
D)  any of the above. 
A)  greater than zero. 
B)  less than zero. 
C)  equal to zero. 
D)  any of the above.

Question 19

When a vapor condenses, the entropy of the gas

Accepted Answer

A)  increases. 
B)  decreases. 
C)  remains the same. 
D)  equals zero. 
A)  increases. 
B)  decreases. 
C)  remains the same. 
D)  equals zero.

Question 20

A Carnot air conditioner with CP = 8 uses 10 kW of power. The heat expelled to the outdoors is

Accepted Answer

A)  10 kW. 
B)  30 kW. 
C)  80 kW. 
D)  90 kW. 
A)  10 kW. 
B)  30 kW. 
C)  80 kW. 
D)  90 kW.

Exam 21: Thermodynamics

A heat engine produces a power output of 1.5 * 105 W when it receives 50.0 MJ of heat per minute. The efficiency of the engine is

The change in entropy when 55 g of ice at 0°C melts (the heat of fusion is 3.34 * 105 J/kg) to water at 0°C is

An ideal gas is heated in a closed container. The net work done on the system

In an adiabatic expansion of an ideal gas, 150 J of work is performed on the surroundings. The heat added or removed from the gas is

A heat pump with a coefficient of performance of 10 used 50 kW of power. The heat delivered to the house is

In an adiabatic expansion of an ideal gas, 150 J of work is performed on the surroundings. The change in the internal energy of the gas is

During an adiabatic process

The coefficient of performance, CP, for a heat pump is defined as

During an isobaric (constant pressure) expansion, the volume of an ideal gas increases from 0.15 m3 to 0.35 m3. The pressure during the expansion is 150 kPa. The work done by the system is

During an isothermal process involving an ideal gas, 150 J of heat is removed from the system. The work done by the gas is

For each 150 Btu a heat engine absorbs, the system exhausts 64 Btu. The efficiency of the engine is

The efficiency of a Carnot cycle is 0.20 when operating with a hot reservoir of 93°C. If the temperature of the cold reservoir is maintained, the temperature of the hot reservoir necessary to double the efficiency is

The perpetual motion machine of the first kind is

Two Carnot cycles have the same efficiency. The first operates between Th = 200°C and Tc = 100°C and the second operates with a hot reservoir of Th = 400°C. The lower reservoir's temperature is

The graph here represents a p-V diagram where the x axis is the volume in units of 10-3 m3 and the y axis is the pressure in units of 105 N/m2. The work done by the gas as it contracts from (p2, V2) to (p1, V1) along the path indicated is

A container of 1.5 kg of water with a specific heat of 4186 J/(kg·°C) is heated from 25°C to 95°C. The change in the entropy of the water is

The graph here represents a p-V diagram where the x axis is the volume in units of 10-3 m3 and the y axis is the pressure in units of 105 N/m2. The work done by the gas as it expands from (p1, V1) to (p2, V2) along the path indicated is

During an adiabatic process the change in the temperature of the system is

When a vapor condenses, the entropy of the gas

A Carnot air conditioner with CP = 8 uses 10 kW of power. The heat expelled to the outdoors is

Space, Time, and Mass

Motion Along a Straight Line

Vectors

Motion in Two and Three Dimensions

Newtons Laws of Motion

Further Applications of Newtons Laws

Work and Energy

Conservation of Energy

Gravitation

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Collisions

Rotation of a Rigid Body

Dynamics of a Rigid Body

Statics and Elasticity

Oscillations

Waves

Sound

Fluid Mechanics

The Ideal Gas

Heat

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The Electric Field

Gauss Law

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The Theory of Special Relativity

Quanta of Light

Spectral Lines, Bohrs Theory, and Quantum Mechanics

Quantum Structure of Atoms, Molecules, and Solids

Nuclei

Elementary Particles and Cosmology

Filters

A heat engine produces a power output of 1.5 * 10⁵ W when it receives 50.0 MJ of heat per minute. The efficiency of the engine is

The change in entropy when 55 g of ice at 0°C melts (the heat of fusion is 3.34 * 10⁵ J/kg) to water at 0°C is

During an isobaric (constant pressure) expansion, the volume of an ideal gas increases from 0.15 m³ to 0.35 m³. The pressure during the expansion is 150 kPa. The work done by the system is

Two Carnot cycles have the same efficiency. The first operates between T_h = 200°C and T_c = 100°C and the second operates with a hot reservoir of T_h = 400°C. The lower reservoir's temperature is

The graph here represents a p-V diagram where the x axis is the volume in units of 10^-3 m³and the y axis is the pressure in units of 10⁵ N/m². The work done by the gas as it contracts from (p₂, V₂) to (p₁, V₁) along the path indicated is

The graph here represents a p-V diagram where the x axis is the volume in units of 10^-3 m³and the y axis is the pressure in units of 10⁵ N/m². The work done by the gas as it expands from (p₁, V₁) to (p₂, V₂) along the path indicated is