Question 1

The gas in a perfectly insulated but flexible container does work at a rate of $13 \mathrm {~W} .$ At what rate is the internal (thermal)energy of the gas changing?

Accepted Answer

A) -13 W 
B) 13 W 
C) 0 W 
D) 6.5 W 
A) -13 W 
B) 13 W 
C) 0 W 
D) 6.5 W

Question 2

A cylinder contains 8.8 moles of ideal gas, initially at a temperature of 126°C. The cylinder is provided with a frictionless piston, which maintains a constant pressure of $5.3 \times 10 ^ { 5 } \mathrm {~Pa}$ on the gas. The gas is cooled until its temperature has decreased to $27 ^ { \circ } \mathrm { C }$ For the gas $\mathrm { C } _ { \mathrm { V } } = 13.73 \mathrm {~J} / \mathrm { mol } \cdot \mathrm { K }$ The ideal gas constant is R = 8.314 J/mol ? K. For this process, calculate:
(a)the work done by gas
(b)the net change in the internal (thermal)energy of the gas
(c)the heat transferred to the gas.

Accepted Answer

(a)-7200 J

Question 3

An ideal reversible heat pump is taking heat from the outside air at -10.0°C and discharging it into the house at 18.0°C. What is the coefficient of performance of this heat pump?

Accepted Answer

A) 10.4 
B) 9.44 
C) 0.644 
D) 0.533 
E) 0.0962 
A) 10.4 
B) 9.44 
C) 0.644 
D) 0.533 
E) 0.0962

Question 4

A monatomic ideal gas undergoes an isothermal expansion at 300 K, as the volume increased from $0.010 \mathrm {~m} ^ { 3 }$ to $0.040 \mathrm {~m} ^ { 3 }$ The final pressure is $130 \mathrm { kPa } \text {. }$ What is the change in the internal (thermal)energy of the gas during this process? (R = 8.31 J/mol ? K)

Accepted Answer

A) 0.0 kJ 
B) 3.6 kJ 
C) 7.2 kJ 
D) -3.6 kJ 
E) -7.2 kJ 
A) 0.0 kJ 
B) 3.6 kJ 
C) 7.2 kJ 
D) -3.6 kJ 
E) -7.2 kJ

Question 5

A cylinder contains 13 moles of an ideal gas at a temperature of 300 K. The gas is compressed at constant pressure until the final volume equal 0.70 times the initial volume. The molar heat capacity at constant volume of the gas is 24.0 J/mol ∙ K. What is the change in the internal (thermal)energy of the gas during this process? (R = 8.31 J/mol ∙ K)

Accepted Answer

A) -28 kJ 
B) -38 kJ 
C) 28 kJ 
D) 38 kJ 
E) -9.7 kJ 
A) -28 kJ 
B) -38 kJ 
C) 28 kJ 
D) 38 kJ 
E) -9.7 kJ

Question 6

An expansion process on an ideal diatomic ideal gas for which CV = 5/2 R has a linear path between the initial and final coordinates on a pV diagram. The coordinates of the initial state are: the pressure is $300 \mathrm { kPa } \text {, }$ the volume is $0.030 \mathrm {~m} ^ { 3 } ,$ and the temperature is $390 \mathrm {~K} .$ The final pressure is $150 \mathrm { kPa }$ and the final temperature is $340 \mathrm {~K} .$ What is the change in the internal (thermal)energy of the gas, during this process? (R = 8.31 J/mol ? K)

Accepted Answer

A) -2900 J 
B) -1700 J 
C) 2900 J 
D) 1700 J 
E) 0 J 
A) -2900 J 
B) -1700 J 
C) 2900 J 
D) 1700 J 
E) 0 J

Question 7

The temperature in your classroom is closest to

Accepted Answer

A) 68 K. 
B) 68°C. 
C) 50°C. 
D) 295 K. 
A) 68 K. 
B) 68°C. 
C) 50°C. 
D) 295 K.

Question 8

A sealed rigitd tank contains 30 moles of an ideal gas, at an initial temperature of $270 \mathrm {~K}$ The pressure of the gas is increased until the final pressure equals 1.40 times the initial pressure. The heat capacity at constant pressure of the gas is $32.0 \mathrm {~J} / \mathrm { mol } \cdot \mathrm { K }$ What is the change in the internal (thermal)energy of the gas during this process? (R = 8.31 J/mol ? K)

Accepted Answer

A) 77 kJ 
B) 100 kJ 
C) 130 kJ 
D) -50 kJ 
E) -23 kJ 
A) 77 kJ 
B) 100 kJ 
C) 130 kJ 
D) -50 kJ 
E) -23 kJ

Question 9

During each cycle, a refrigerator removes 20.0 kJ of heat from the freezing compartment and ejects 24.0 kJ into a room.
(a)How much work per cycle is required each cycle to run this refrigerator?
(b)What is the coefficient of performance of this refrigerator?

Accepted Answer

The answer of During each cycle, a refrigerator removes 20.0...

Question 10

An ideal gas undergoes the process a?b?c?a shown in the pV diagram. The heat gained by the gas in process a?b is 546 J, while in process $b \rightarrow c$ the gas loses 62.0 J of heat. In process a?b the gas performs $310 \mathrm {~J}$ of work, while in process c?a 223 J of work is done on the gas. How much heat is gained by the gas in process c?a?

Accepted Answer

A) -397 J 
B) -62 J 
C) 223 J 
D) 18 J 
E) -236 J 
A) -397 J 
B) -62 J 
C) 223 J 
D) 18 J 
E) -236 J

Question 11

A person running in place on an exercise machine for 10 min uses up 17 kcal (food calories). Another person exercises by repeatedly lifting two 2.5-kg weights a distance of 50 cm. How many repetitions of this exercise are equivalent to 10 minutes of running in place? Assume that the person uses negligible energy in letting down the weights after each lift. (1 cal = 4.186 J)

Accepted Answer

A) 730 
B) 1450 
C) 1500 
D) 2200 
E) 2900 
A) 730 
B) 1450 
C) 1500 
D) 2200 
E) 2900

Question 12

The "hot shot" heat engine operating between 40°C and 380°C has an efficiency that is 60% of that of an ideal Carnot engine operating between the same temperatures. If the "hot shot" engine absorbs heat at a rate of 60 kW, at what rate does it exhaust heat?

Accepted Answer

A) 36 kW 
B) 41 kW 
C) 57 kW 
D) 60 kW 
A) 36 kW 
B) 41 kW 
C) 57 kW 
D) 60 kW

Question 13

An external heat source supplies heat to a system at a rate of 187 W as the system does work at a rate of 131 W. At what rate is the internal (thermal)energy of the system changing?

Accepted Answer

A) -56 W 
B) 320 W 
C) 56 W 
D) 190 W 
E) -320 W 
A) -56 W 
B) 320 W 
C) 56 W 
D) 190 W 
E) -320 W

Question 14

What is absolute zero on the (a)Celsius scale and (b)on the Fahrenheit scale?

Accepted Answer

The answer of What is absolute zero on the (a)Celsius...

Question 15

Nitrogen boils at -196°C. What is the corresponding temperature in the Fahrenheit scale?

Accepted Answer

A) -315°F 
B) -196°F 
C) -346°F 
D) -290°F 
E) -321°F 
A) -315°F 
B) -196°F 
C) -346°F 
D) -290°F 
E) -321°F

Question 16

In an adiabatic compression, 200 J of work is done on a gas. What is the change in internal (thermal)energy of the gas during this compression?

Accepted Answer

A) 0 J 
B) 100 J 
C) 200 J 
D) -200 J 
A) 0 J 
B) 100 J 
C) 200 J 
D) -200 J

Question 17

A Carnot engine operates between two reservoirs with unknown temperatures. If the Carnot engine operates at $67 \%$ efficiency, what is the ratio of the absolute temperatures of the reservoirs, Tc/Th?

Accepted Answer

A) 0.33 
B) 0.0012 
C) 0.0025 
D) 0.67 
A) 0.33 
B) 0.0012 
C) 0.0025 
D) 0.67

Question 18

An ideal Carnot heat engine operates between reservoirs at 1740 K and $150 \mathrm {~K} .$ In each cycle, 260 J of heat energy is rejected to the low temperature reservoir. In each cycle, how much mechanical work W is performed by the engine?

Accepted Answer

The answer of An ideal Carnot heat engine operates between...

Question 19

The ocean thermal energy conversion project uses the surface water near tropical islands with a temperature of 20°C as the hot temperature reservoir, and the water at some depth, with a temperature of 5.0°C, as the cold temperature reservoir for a heat engine. What is the maximum possible efficiency of an engine running between those two temperatures?

Accepted Answer

A) 4.7% 
B) 5.1% 
C) 7.9% 
D) 15% 
E) 30% 
A) 4.7% 
B) 5.1% 
C) 7.9% 
D) 15% 
E) 30%

Question 20

A heat engine having the maximum possible efficiency has an efficiency of 35.0% when operating between two heat reservoirs. If the temperature of the hot reservoir is 700 K, what is the temperature of the cold reservoir?

Accepted Answer

A) 200 K 
B) 245 K 
C) 350 K 
D) 455 K 
E) 600 K 
A) 200 K 
B) 245 K 
C) 350 K 
D) 455 K 
E) 600 K

Exam 11: Using Energy

The gas in a perfectly insulated but flexible container does work at a rate of 13 W.13 \mathrm {~W} .13 W. At what rate is the internal (thermal)energy of the gas changing?

An ideal reversible heat pump is taking heat from the outside air at -10.0°C and discharging it into the house at 18.0°C. What is the coefficient of performance of this heat pump?

The temperature in your classroom is closest to

During each cycle, a refrigerator removes 20.0 kJ of heat from the freezing compartment and ejects 24.0 kJ into a room. (a)How much work per cycle is required each cycle to run this refrigerator? (b)What is the coefficient of performance of this refrigerator?

The "hot shot" heat engine operating between 40°C and 380°C has an efficiency that is 60% of that of an ideal Carnot engine operating between the same temperatures. If the "hot shot" engine absorbs heat at a rate of 60 kW, at what rate does it exhaust heat?

An external heat source supplies heat to a system at a rate of 187 W as the system does work at a rate of 131 W. At what rate is the internal (thermal)energy of the system changing?

What is absolute zero on the (a)Celsius scale and (b)on the Fahrenheit scale?

Nitrogen boils at -196°C. What is the corresponding temperature in the Fahrenheit scale?

In an adiabatic compression, 200 J of work is done on a gas. What is the change in internal (thermal)energy of the gas during this compression?

A Carnot engine operates between two reservoirs with unknown temperatures. If the Carnot engine operates at 67%67 \%67% efficiency, what is the ratio of the absolute temperatures of the reservoirs, Tc/Th?

An ideal Carnot heat engine operates between reservoirs at 1740 K and 150 K.150 \mathrm {~K} .150 K. In each cycle, 260 J of heat energy is rejected to the low temperature reservoir. In each cycle, how much mechanical work W is performed by the engine?

A heat engine having the maximum possible efficiency has an efficiency of 35.0% when operating between two heat reservoirs. If the temperature of the hot reservoir is 700 K, what is the temperature of the cold reservoir?

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The gas in a perfectly insulated but flexible container does work at a rate of $13 \mathrm {~W} .$ At what rate is the internal (thermal)energy of the gas changing?

A Carnot engine operates between two reservoirs with unknown temperatures. If the Carnot engine operates at $67 \%$ efficiency, what is the ratio of the absolute temperatures of the reservoirs, T_c/T_h?

An ideal Carnot heat engine operates between reservoirs at 1740 K and $150 \mathrm {~K} .$ In each cycle, 260 J of heat energy is rejected to the low temperature reservoir. In each cycle, how much mechanical work W is performed by the engine?