Question 1

The figure shows a pV diagram for a cycle of a thermodynamic engine for which QH = 59 J.What is the thermal efficiency of the engine?

Accepted Answer

A) 17% 
B) 34% 
C) 8.5% 
D) 14% 
A) 17% 
B) 34% 
C) 8.5% 
D) 14%

Question 2

If the efficiency of a Carnot engine were to be 100%,the cool reservoirs would have to be

Accepted Answer

A) at absolute zero. 
B) at 0°C. 
C) at 100°C. 
D) infinitely hot. 
A) at absolute zero. 
B) at 0°C. 
C) at 100°C. 
D) infinitely hot.

Question 3

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at $1.76 \mathrm {~K}$ has an efficiency of $11.0 \%$ What is the temperature of the warm reservoir?

Accepted Answer

A) 1.98 K 
B) 0.180 K 
C) 157 K 
D) 0.160 K 
A) 1.98 K 
B) 0.180 K 
C) 157 K 
D) 0.160 K

Question 4

A thermodynamic engine has an efficiency of 35.0% and receives 150 J of energy per cycle.
(a)How much work does it do in each cycle?
(b)How much thermal energy does it "waste" in each cycle?

Accepted Answer

(a)52.5 J

Question 5

A gas follows the pV trajectory shown in Figure 16.2.How much work is done per cycle by the gas if the gas in a thermodynamic engine follows the cycle shown in the pV diagram.How much work does this engine do each cycle if p0 = $5.4 \text { atm? }$

Accepted Answer

A) 220 J 
B) 440 J 
C) 870 J 
D) 1100 J 
A) 220 J 
B) 440 J 
C) 870 J 
D) 1100 J

Question 6

Which of the following is a false statement?

Accepted Answer

A) Entropy is a quantitative measure of disorder. 
B) The total entropy change in one cycle of a Carnot engine is zero. 
C) The entropy of an isolated system remains constant. 
D) Entropy can be measured in units of J/K. 
A) Entropy is a quantitative measure of disorder. 
B) The total entropy change in one cycle of a Carnot engine is zero. 
C) The entropy of an isolated system remains constant. 
D) Entropy can be measured in units of J/K.

Question 7

On a cold winter day,the outside temperature is -20°C and the inside temperature is maintained at 20°C.There is a net thermal energy flow to the outside through the walls,roof,etc.,of 25 kW.What is the rate of increase of the entropy of the universe as a result of this energy flow?

Accepted Answer

A) 13 W/K 
B) 25 W/K 
C) 85 W/K 
D) 99 W/K 
E) 0 W/K 
A) 13 W/K 
B) 25 W/K 
C) 85 W/K 
D) 99 W/K 
E) 0 W/K

Question 8

An ideal Carnot engine operates between a high temperature reservoir at $492 \mathrm {~K}$ and a river with water at $290 \mathrm {~K} .$ If it absorbs $4000 \mathrm {~J}$ of energy each cycle,how much work per cycle does it perform?

Accepted Answer

A) 1642 J 
B) 2358 J 
C) 1483 J 
D) 2517 J 
A) 1642 J 
B) 2358 J 
C) 1483 J 
D) 2517 J

Question 9

An ideal Carnot engine extracts 529 J of energy from a high-temperature reservoir during each cycle,and rejects $225 \mathrm {~J}$ of energy to a low-temperature reservoir during the same cycle.What is the efficiency of the engine?

Accepted Answer

A) 0.57 
B) 1.35 
C) 2.35 
D) 0.7 
A) 0.57 
B) 1.35 
C) 2.35 
D) 0.7

Question 10

For a certain ideal Carnot engine,the hot reservoir is 35 C° higher than the cold reservoir.If this engine is to have an efficiency of 20%,what must be the temperature of the hot reservoir?

Accepted Answer

A) 70.0 K 
B) 140 K 
C) 175 K 
D) 210 K 
E) 245 K 
A) 70.0 K 
B) 140 K 
C) 175 K 
D) 210 K 
E) 245 K

Question 11

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at $1.76 \mathrm {~K}$ has an efficiency of $40.0 \%$ What is the temperature of the warm reservoir?

Accepted Answer

A) 2.93 K 
B) 0.0500 K 
C) 106 K 
D) 0.0400 K 
A) 2.93 K 
B) 0.0500 K 
C) 106 K 
D) 0.0400 K

Question 12

A real (non-Carnot)thermodynamic engine,operating between thermal energy reservoirs at temperatures of 450 K and 270 K,performs 3.3 kJ of net work,and rejects 8.2 kJ of energy in a single cycle.
(a)What is the thermal efficiency of this thermodynamic engine?
(b)What is the maximum efficiency it could possibly have?

Accepted Answer

The answer of A real (non-Carnot)thermodynamic engine,operating between thermal energy...

Question 13

A container of ideal gas at STP undergoes an isothermal expansion and its entropy changes by 3.7 J/K.How much work does it do?

Accepted Answer

A) 0.0 J 
B) 1.0 × 103 J 
C) -1.0 × 103 J 
D) 1.4 × 103 J 
E) -1.4 × 103 J 
A) 0.0 J 
B) 1.0 × 103 J 
C) -1.0 × 103 J 
D) 1.4 × 103 J 
E) -1.4 × 103 J

Question 14

An ideal gas undergoes an isothermal expansion.During this process,its entropy

Accepted Answer

A) decreases. 
B) remains unchanged. 
C) increases. 
D) cannot be predicted from the data given. 
A) decreases. 
B) remains unchanged. 
C) increases. 
D) cannot be predicted from the data given.

Question 15

A 15.0-kg block of ice at 0.00°C falls into Lake Superior,which is a fresh water lake.The lake water is at 10.0°C,and the latent heat of fusion for ice is 3.34 × 105 J/kg.Find the change in entropy due to the melting of the ice (a)of the block of ice,(b)of the lake,and (c)of the system consisting of the lake and the ice.(d)Is your answer to part (c)consistent with the reversibility or irreversibility of the melting process?

Accepted Answer

(a)+1.84 × 10⁴ J/K (

Question 16

A thermodynamic pump absorbs thermal energy from the atmosphere at a rate of 30 kW.If work is being done to run this thermodynamic pump at a rate of 7.7 kW,what is the coefficient of performance (COP)of the thermodynamic pump?

Accepted Answer

A) 3.9 
B) 4.9 
C) 2.9 
D) 0.26 
E) 22 
A) 3.9 
B) 4.9 
C) 2.9 
D) 0.26 
E) 22

Question 17

When 0.50 kg of water at 0°C freezes,what is the change in entropy of the water? The latent heat of fusion of water is 33,400 J/kg.

Accepted Answer

A) 0 J/K 
B) 610 J/K 
C) -610 J/K 
D) -17,000 J/K 
E) 17,000 J/K 
A) 0 J/K 
B) 610 J/K 
C) -610 J/K 
D) -17,000 J/K 
E) 17,000 J/K

Question 18

A refrigerator has a coefficient of performance equal to 4.2.How much work must be done on the operating gas in the refrigerator in order to remove 250 J of energy from the interior compartment?

Accepted Answer

A) 60 J 
B) 120 J 
C) 250 J 
D) 480 J 
E) 1050 J 
A) 60 J 
B) 120 J 
C) 250 J 
D) 480 J 
E) 1050 J

Question 19

An ideal Carnot engine is operated as an air conditioner to cool a house in the summer.The air conditioner removes $14 \text { kJ }$ of thermal energy per second from the house,and maintains the inside temperature at $293 \mathrm {~K} \text {, }$ while the outside temperature is $369 \mathrm {~K} .$ The power required to run the air conditioner under these operating conditions is closest to

Accepted Answer

A) 3600 W. 
B) 4400 W. 
C) 5100 W. 
D) 5800 W. 
E) 6600 W. 
A) 3600 W. 
B) 4400 W. 
C) 5100 W. 
D) 5800 W. 
E) 6600 W.

Question 20

An ideal Carnot engine has an efficiency of 83.0% and performs 4500 J of work every cycle.How much energy is discharged to the lower temperature reservoir every cycle?

Accepted Answer

A) 920 J 
B) 830 J 
C) 740 J 
D) 3700 J 
E) 5400 J 
A) 920 J 
B) 830 J 
C) 740 J 
D) 3700 J 
E) 5400 J

Exam 14: Second Law of Thermodynamics

The figure shows a pV diagram for a cycle of a thermodynamic engine for which QH = 59 J.What is the thermal efficiency of the engine?

If the efficiency of a Carnot engine were to be 100%,the cool reservoirs would have to be

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at 1.76 K1.76 \mathrm {~K}1.76 K has an efficiency of 11.0%11.0 \%11.0% What is the temperature of the warm reservoir?

A thermodynamic engine has an efficiency of 35.0% and receives 150 J of energy per cycle. (a)How much work does it do in each cycle? (b)How much thermal energy does it "waste" in each cycle?

A gas follows the pV trajectory shown in Figure 16.2.How much work is done per cycle by the gas if the gas in a thermodynamic engine follows the cycle shown in the pV diagram.How much work does this engine do each cycle if p0 = 5.4 atm? 5.4 \text { atm? }5.4 atm?

Which of the following is a false statement?

On a cold winter day,the outside temperature is -20°C and the inside temperature is maintained at 20°C.There is a net thermal energy flow to the outside through the walls,roof,etc.,of 25 kW.What is the rate of increase of the entropy of the universe as a result of this energy flow?

An ideal Carnot engine operates between a high temperature reservoir at 492 K492 \mathrm {~K}492 K and a river with water at 290 K.290 \mathrm {~K} .290 K. If it absorbs 4000 J4000 \mathrm {~J}4000 J of energy each cycle,how much work per cycle does it perform?

An ideal Carnot engine extracts 529 J of energy from a high-temperature reservoir during each cycle,and rejects 225 J225 \mathrm {~J}225 J of energy to a low-temperature reservoir during the same cycle.What is the efficiency of the engine?

For a certain ideal Carnot engine,the hot reservoir is 35 C° higher than the cold reservoir.If this engine is to have an efficiency of 20%,what must be the temperature of the hot reservoir?

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at 1.76 K1.76 \mathrm {~K}1.76 K has an efficiency of 40.0%40.0 \%40.0% What is the temperature of the warm reservoir?

A container of ideal gas at STP undergoes an isothermal expansion and its entropy changes by 3.7 J/K.How much work does it do?

An ideal gas undergoes an isothermal expansion.During this process,its entropy

A thermodynamic pump absorbs thermal energy from the atmosphere at a rate of 30 kW.If work is being done to run this thermodynamic pump at a rate of 7.7 kW,what is the coefficient of performance (COP)of the thermodynamic pump?

When 0.50 kg of water at 0°C freezes,what is the change in entropy of the water? The latent heat of fusion of water is 33,400 J/kg.

A refrigerator has a coefficient of performance equal to 4.2.How much work must be done on the operating gas in the refrigerator in order to remove 250 J of energy from the interior compartment?

An ideal Carnot engine has an efficiency of 83.0% and performs 4500 J of work every cycle.How much energy is discharged to the lower temperature reservoir every cycle?

Introduction

Kinematics: Motion in One Dimension

Newtonian Mechanics

Applying Newtons Laws

Circular Motion

Impulse and Linear Momentum

Work and Energy

Extended Bodies at Rest

Rotational Motion

Gases

Static Fluids

Fluids in Motion

First Law of Thermodynamics

Electric Charge force and Energy

The Electric Field

Dc Circuits

Magnetism

Electromagnetic Induction

Vibrational Motion

Mechanical Waves

Reflection and Refraction

Mirrors and Lenses

Wave Optics

Electromagnetic Waves

Special Relativity

Quantum Optics

Atomic Physics

Nuclear Physics

Particle Physics

Filters

The figure shows a pV diagram for a cycle of a thermodynamic engine for which Q_H = 59 J.What is the thermal efficiency of the engine?

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at $1.76 \mathrm {~K}$ has an efficiency of $11.0 \%$ What is the temperature of the warm reservoir?

An ideal Carnot engine operates between a high temperature reservoir at $492 \mathrm {~K}$ and a river with water at $290 \mathrm {~K} .$ If it absorbs $4000 \mathrm {~J}$ of energy each cycle,how much work per cycle does it perform?

An ideal Carnot engine extracts 529 J of energy from a high-temperature reservoir during each cycle,and rejects $225 \mathrm {~J}$ of energy to a low-temperature reservoir during the same cycle.What is the efficiency of the engine?

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at $1.76 \mathrm {~K}$ has an efficiency of $40.0 \%$ What is the temperature of the warm reservoir?