Question 1

The work done on an ideal gas system in an isothermal process is -400 J. What is the change in internal (thermal)energy of the gas?

Accepted Answer

A) 0 J 
B) -400 J 
C) 400 J 
D) 200 J 
A) 0 J 
B) -400 J 
C) 400 J 
D) 200 J

Question 2

A person consumes a snack containing 14 food calories (14 kcal). What is the power this food produces if it is to be "burned off" due to exercise in 6 hours? (1 cal = 4.186 J)

Accepted Answer

A) 2.7 W 
B) 9763 W 
C) 0.6 W 
D) 0.0027 W 
A) 2.7 W 
B) 9763 W 
C) 0.6 W 
D) 0.0027 W

Question 3

During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal (thermal)energy of the gas?

Accepted Answer

A) 0 J 
B) 2.5 J 
C) 5.0 J 
D) 10 J 
A) 0 J 
B) 2.5 J 
C) 5.0 J 
D) 10 J

Question 4

One of the most efficient engines built so far has the following characteristics: The combustion chamber temperature is 1900°C, the exhaust temperature = 430°C, 7.0 × 109 cal of fuel produces 1.4 × 1010 J of work in one hour. (1 cal = 4.186 J)
(a)What is the actual efficiency of this engine?
(b)What is the power output of this engine?
(c)What would be the maximum possible efficiency for an engine using the same temperature extremes?

Accepted Answer

(a)48% (b)

Question 5

Express a body temperature 98.6°F in Celsius degrees.

Accepted Answer

A) 37.0°C 
B) 45.5°C 
C) 66.6°C 
D) 72.6°C 
A) 37.0°C 
B) 45.5°C 
C) 66.6°C 
D) 72.6°C

Question 6

A heat engine has an efficiency of 31.4% and receives 8.72 kJ of heat per cycle.
(a)How much work does it perform in each cycle?
(b)How much heat does it exhaust in each cycle?

Accepted Answer

(a)2.74 Kj

Question 7

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

Accepted Answer

The answer of A heat engine has an efficiency of...

Question 8

A 40.0-L container is divided into two equal parts by a rubber membrane. One half of the container has 1.50 moles of an ideal monatomic gas at 250 K, and the other half is a vacuum. The container is well insulated, so there is no exchange of heat with the surroundings. The membrane breaks, and eventually the gas reaches a new equilibrium condition occupying the entire volume. What is the final temperature of the gas?

Accepted Answer

A) 100 K 
B) 125 K 
C) 157 K 
D) 180 K 
E) 250 K 
A) 100 K 
B) 125 K 
C) 157 K 
D) 180 K 
E) 250 K

Question 9

A Carnot air conditioner has a coefficient of performance of 17.0 and removes 72.0 MJ of heat from the interior of a house every hour. How much power does it consume?

Accepted Answer

A) 1180 W 
B) 1320 W 
C) 520 kW 
D) 3.14 MW 
E) 1.25 MW 
A) 1180 W 
B) 1320 W 
C) 520 kW 
D) 3.14 MW 
E) 1.25 MW

Question 10

When water at 0°C freezes, the entropy of the water

Accepted Answer

A) increases. 
B) decreases. 
C) remains constant. 
D) could either increase or decrease; it depends on other factors. 
A) increases. 
B) decreases. 
C) remains constant. 
D) could either increase or decrease; it depends on other factors.

Question 11

A heat engine absorbs 64 kcal of heat each cycle and exhausts 42 kcal.
(a)What is the efficiency of this engine?
(b)How much work does this engine do per cycle?

Accepted Answer

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

Question 12

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 13

A certain automobile engine takes in 4.00 kJ of heat and performs 1.10 kJ of mechanical work in each cycle.
(a)Calculate the engine's efficiency.
(b)How much heat is "wasted" in each cycle?

Accepted Answer

The answer of A certain automobile engine takes in 4.00...

Question 14

A cylinder contains 10 moles of an ideal gas at a temperature of 300 K. The gas is compressed at constant pressure until the final volume equals 0.77 times the initial volume. The molar heat capacity at constant volume of the gas is 24.0 J/mol ∙ K and R = 8.31 J/mol ∙ K . How much heat is absorbed by the gas during this process? (R = 8.31 J/mol ∙ K)

Accepted Answer

A) -22 kJ 
B) -17 kJ 
C) 22 kJ 
D) 17 kJ 
E) -5.7 kJ 
A) -22 kJ 
B) -17 kJ 
C) 22 kJ 
D) 17 kJ 
E) -5.7 kJ

Question 15

During each cycle, a heat engine takes in 4.0 J of heat, does 1.0 J of work, and expels 3.0 J of heat. What is its efficiency?

Accepted Answer

The answer of During each cycle, a heat engine takes...

Question 16

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

A 10-L flask and a 1-L flask each contain two moles of ideal diatomic gas (but not the same gas)at 25°C. Which of the following statements about these gases must be true? (There could be more than one correct choice.)

Accepted Answer

A) The internal (thermal)energy of the gas in both flasks is the same. 
B) The internal (thermal)energy of the gas in the larger flask is greater than the internal (thermal)energy of the gas in the smaller flask. 
C) The internal (thermal)energy of the gas in the smaller flask is greater than the internal (thermal)energy of the gas in the larger flask. 
D) The molecules in the larger flask have the same root-mean-square speed as those in the smaller flask. 
E) The molecules in the smaller flask have the same average kinetic energy per molecule as those in the larger flask. 
A) The internal (thermal)energy of the gas in both flasks is the same. 
B) The internal (thermal)energy of the gas in the larger flask is greater than the internal (thermal)energy of the gas in the smaller flask. 
C) The internal (thermal)energy of the gas in the smaller flask is greater than the internal (thermal)energy of the gas in the larger flask. 
D) The molecules in the larger flask have the same root-mean-square speed as those in the smaller flask. 
E) The molecules in the smaller flask have the same average kinetic energy per molecule as those in the larger flask.

Question 18

The temperature changes from 35°F during the night to 75°F during the day. What is the temperature change on the Celsius scale?

Accepted Answer

A) 72 C° 
B) 40 C° 
C) 32 C° 
D) 22 C° 
A) 72 C° 
B) 40 C° 
C) 32 C° 
D) 22 C°

Question 19

Platinum melts at 3215°F. What is the corresponding temperature in the Kelvin scale?

Accepted Answer

A) 2041 K 
B) 2135 K 
C) 2207 K 
D) 2296 K 
E) 3215 K 
A) 2041 K 
B) 2135 K 
C) 2207 K 
D) 2296 K 
E) 3215 K

Question 20

The figure shows a pV diagram of a gas for a complete cycle. During part bc of the cycle, 1190 J of heat flows into a system, and at the same time the system expands against a constant external pressure of $7.00 \times 10 ^ { 4 } \mathrm {~Pa}$ as its volume increases from $0.0200 \mathrm {~m} ^ { 3 }$ to $0.0800 \mathrm {~m} ^ { 3 }$ Calculate the change in internal (thermal)energy of the system during part bc of the cycle. If the change is nonzero, be sure to indicate whether the change is positive or negative.

Accepted Answer

The answer of The figure shows a pV diagram of...

Exam 11: Using Energy

The work done on an ideal gas system in an isothermal process is -400 J. What is the change in internal (thermal)energy of the gas?

A person consumes a snack containing 14 food calories (14 kcal). What is the power this food produces if it is to be "burned off" due to exercise in 6 hours? (1 cal = 4.186 J)

During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal (thermal)energy of the gas?

Express a body temperature 98.6°F in Celsius degrees.

A heat engine has an efficiency of 31.4% and receives 8.72 kJ of heat per cycle. (a)How much work does it perform in each cycle? (b)How much heat does it exhaust in each cycle?

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

A Carnot air conditioner has a coefficient of performance of 17.0 and removes 72.0 MJ of heat from the interior of a house every hour. How much power does it consume?

When water at 0°C freezes, the entropy of the water

A heat engine absorbs 64 kcal of heat each cycle and exhausts 42 kcal. (a)What is the efficiency of this engine? (b)How much work does this engine do per cycle?

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 certain automobile engine takes in 4.00 kJ of heat and performs 1.10 kJ of mechanical work in each cycle. (a)Calculate the engine's efficiency. (b)How much heat is "wasted" in each cycle?

During each cycle, a heat engine takes in 4.0 J of heat, does 1.0 J of work, and expels 3.0 J of heat. What is its efficiency?

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

A 10-L flask and a 1-L flask each contain two moles of ideal diatomic gas (but not the same gas)at 25°C. Which of the following statements about these gases must be true? (There could be more than one correct choice.)

The temperature changes from 35°F during the night to 75°F during the day. What is the temperature change on the Celsius scale?

Platinum melts at 3215°F. What is the corresponding temperature in the Kelvin scale?

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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?