Question 1

A closed 2.0-L container holds 3.0 mol of an ideal gas.If 150 J of heat is added,what is the change in internal energy of the system?

Accepted Answer

A)   zero
B)   100 J
C)   150 J
D)   200 J C

Question 2

Three Carnot engines operate between temperature reservoirs as follows: Engine A: Th = 1300 K,Tc = 1000 K;Engine B: Th = 1000 K,Tc = 700 K;Engine C: Th = 500 K,Tc = 350 K.Which two engines have the same thermal efficiency?

Accepted Answer

A)   A and B
B)   B and C
C)   A and C
D)   No two have the same thermal efficiency. B

Question 3

When gasoline is burned,it gives off 46,000 J/g of heat energy.If an automobile uses 13.0 kg of gasoline per hour with an efficiency of 18%,what is the average horsepower output of the engine? (1 hp = 746 W)

Accepted Answer

A)   47 hp
B)   110 hp
C)   67 hp
D)   40 hp D

Question 4

During each cycle of operation a refrigerator absorbs 45 cal from the freezer compartment and expels 85 cal to the room.If one cycle occurs every 8.0 s,how many minutes will it take to freeze 500 g of water,initially at 0°C? (Lv = 80 cal/g)

Accepted Answer

A)   800 min
B)   4400 min
C)   120 min
D)   150 min

Question 5

A heat engine exhausts 4000 J of heat while performing 2000 J of useful work.What is the efficiency of the engine?

Accepted Answer

A)   15%
B)   33%
C)   40%
D)   60%

Question 6

An avalanche of ice and snow of mass 2500 kg slides a vertical distance of 160 m down a mountainside.If the temperature of the ice,snow,mountain,and surrounding air are all at 0°C,what is the change in entropy of the universe?

Accepted Answer

A)   14,000 J/K
B)   10,000 J/K
C)   1400 J/K
D)   1100 J/K

Question 7

The laws of thermodynamics can be related to the following: (i)the measurement of temperature, (ii)the lowest temperature possible, (iii)conservation of energy,and (iv)only part of heat energy available may be turned into work.Which of these involve the zeroth and third law?

Accepted Answer

A)   (i) and (ii) 
B)   (ii) and (iv) 
C)   (i) and (iii) 
D)   (iii) and (iv)

Question 8

An electrical generating plant operates at a boiler temperature of 200°C and exhausts the unused heat into a nearby river at 20°C.What is the maximum theoretical efficiency of the plant? (0°C = 273 K)

Accepted Answer

A)   61%
B)   38%
C)   21%
D)   41%

Question 9

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 500 K and 300 K will have what maximum efficiency?

Accepted Answer

A)   60%
B)   50%
C)   40%
D)   30%

Question 10

The surface of the Sun is at approximately 5700 K,and the temperature of the Earth's surface is about 290 K.What total entropy change occurs when 2000 J of heat energy is transferred from the Sun to the Earth?

Accepted Answer

A)   5.78 J/K
B)   5.97 J/K
C)   7.24 J/K
D)   6.55 J/K

Question 11

A 2.0-mol ideal gas system is maintained at a constant volume of 4.0 L.If 200 J of heat is added,what is the work done on the system?

Accepted Answer

A)   zero
B)   5.0 J
C)   -6.7 J
D)   20 J

Question 12

In an isobaric process 3.6 × 104 J of work is done on a quantity of gas while its volume changes from 2.3 m3 to 1.1 m3.What is the pressure during this process?

Accepted Answer

A)   1.2 × 104 Pa
B)   2.4 × 104 Pa
C)   3.0 × 104 Pa
D)   8.3 × 104 Pa

Question 13

You have a PV diagram for a device going through a cyclic process forming a closed loop on the diagram.How can you tell from the diagram whether the device is acting as a heat engine and not as a refrigerator?

Accepted Answer

A)   The loop is longer than it is high which means it is acting as a refrigerator.
B)   The loop is higher than it is long which means it is acting as a refrigerator.
C)   The loop proceeds clockwise which means it is acting as a heat engine.
D)   The loop proceeds counterclockwise which means it is acting as a heat engine.

Question 14

In an isothermal process where the pressure decreases from 
To 
,does the internal energy of the system increase,decrease,or stay the same;and does the entropy of the system increase or decrease?

Accepted Answer

A)   The internal energy decreases and the entropy increases.
B)   The internal energy stays the same and the entropy increases.
C)   The internal energy decreases and the entropy decreases.
D)   The internal energy stays the same and the entropy decreases.

Question 15

The laws of thermodynamics can be related to the following: (i)the measurement of temperature, (ii)the lowest temperature possible, (iii)conservation of energy,and (iv)only part of heat energy available may be turned into work.Which of these involve the first and second law?

Accepted Answer

A)   (i) and (ii) 
B)   (ii) and (iv) 
C)   (i) and (iii) 
D)   (iii) and (iv)

Question 16

A quantity of monatomic ideal gas expands adiabatically from a volume of 2.0 liters to 4.0 liters.If the initial pressure is P0,what is the final pressure?

Accepted Answer

A)   9.0P0
B)   6.2P0
C)   0.31P0
D)   0.16P0

Question 17

A gasoline engine with an efficiency of 40.0% operates between a high temperature T1 and a low temperature T2 = 320 K.If this engine operates with Carnot efficiency,what is the high-side temperature T1?

Accepted Answer

A)   1070 K
B)   868 K
C)   533 K
D)   457 K

Question 18

A turbine takes in 1000 K steam and exhausts the steam at a temperature of 400 K.What is the maximum theoretical efficiency of this system?

Accepted Answer

A)   24%
B)   40%
C)   50%
D)   60%

Question 19

Consider a Carnot cycle starting at the state of highest pressure and smallest volume.Call the isothermal expansion that starts at this state step 1,the adiabatic expansion which follows step 2,the isothermal compression that then follows step 3,and the adiabatic compression which returns the system to the initial state step 4.In which step does the entropy of the system increase?

Accepted Answer

A)   1
B)   2
C)   3
D)   4

Question 20

An electrical generating plant operates at a boiler temperature of 220°C and exhausts the unused heat into a nearby river at 19°C.If the generating plant has a power output of 800 megawatts (MW)and if the actual efficiency is 3/5 the theoretical efficiency,how much heat per second must be delivered to the boiler? (0°C = 273 K)

Accepted Answer

A)   5200 MW
B)   1810 MW
C)   3270 MW
D)   2620 MW

Exam 16: Electrical Energy and Capacitance: Part A

A closed 2.0-L container holds 3.0 mol of an ideal gas.If 150 J of heat is added,what is the change in internal energy of the system?

Three Carnot engines operate between temperature reservoirs as follows: Engine A: T_h = 1300 K,T_c = 1000 K;Engine B: T_h = 1000 K,T_c = 700 K;Engine C: T_h = 500 K,T_c = 350 K.Which two engines have the same thermal efficiency?

When gasoline is burned,it gives off 46,000 J/g of heat energy.If an automobile uses 13.0 kg of gasoline per hour with an efficiency of 18%,what is the average horsepower output of the engine? (1 hp = 746 W)

During each cycle of operation a refrigerator absorbs 45 cal from the freezer compartment and expels 85 cal to the room.If one cycle occurs every 8.0 s,how many minutes will it take to freeze 500 g of water,initially at 0°C? (L_v = 80 cal/g)

A heat engine exhausts 4000 J of heat while performing 2000 J of useful work.What is the efficiency of the engine?

An avalanche of ice and snow of mass 2500 kg slides a vertical distance of 160 m down a mountainside.If the temperature of the ice,snow,mountain,and surrounding air are all at 0°C,what is the change in entropy of the universe?

The laws of thermodynamics can be related to the following: (i) the measurement of temperature, (ii) the lowest temperature possible, (iii) conservation of energy,and (iv) only part of heat energy available may be turned into work.Which of these involve the zeroth and third law?

An electrical generating plant operates at a boiler temperature of 200°C and exhausts the unused heat into a nearby river at 20°C.What is the maximum theoretical efficiency of the plant? (0°C = 273 K)

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 500 K and 300 K will have what maximum efficiency?

The surface of the Sun is at approximately 5700 K,and the temperature of the Earth's surface is about 290 K.What total entropy change occurs when 2000 J of heat energy is transferred from the Sun to the Earth?

A 2.0-mol ideal gas system is maintained at a constant volume of 4.0 L.If 200 J of heat is added,what is the work done on the system?

In an isobaric process 3.6 × 10⁴ J of work is done on a quantity of gas while its volume changes from 2.3 m³ to 1.1 m³.What is the pressure during this process?

You have a PV diagram for a device going through a cyclic process forming a closed loop on the diagram.How can you tell from the diagram whether the device is acting as a heat engine and not as a refrigerator?

In an isothermal process where the pressure decreases from To ,does the internal energy of the system increase,decrease,or stay the same;and does the entropy of the system increase or decrease?

The laws of thermodynamics can be related to the following: (i) the measurement of temperature, (ii) the lowest temperature possible, (iii) conservation of energy,and (iv) only part of heat energy available may be turned into work.Which of these involve the first and second law?

A quantity of monatomic ideal gas expands adiabatically from a volume of 2.0 liters to 4.0 liters.If the initial pressure is P₀,what is the final pressure?

A gasoline engine with an efficiency of 40.0% operates between a high temperature T₁ and a low temperature T₂ = 320 K.If this engine operates with Carnot efficiency,what is the high-side temperature T₁?

A turbine takes in 1000 K steam and exhausts the steam at a temperature of 400 K.What is the maximum theoretical efficiency of this system?