Question 1

Order in one part of the universe can only be produced at the expense of disorder in another part.

Accepted Answer

A) True 
 B)False  True

Question 2

A heat engine operating at maximum efficiency has an efficiency of 35.0%. 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 D

Question 3

A refrigerator has a COP of 2.5. If it removes 7.7 MJ of heat in 25. minutes,
(a) what is the minimum power motor to operate the refrigerator?
(b) what is its efficiency if it were a reversible engine?

Accepted Answer

(a)2.1 kW
(b)29.% efficiency

Question 4

What is meant by "the heat death of the universe"?

Accepted Answer

A)  The universe will end in a giant inferno. 
B)  The universe will reach thermal equilibrium. 
C)  Some day the sun will explode and we will all burn. 
D)  Some day the sun will cease to provide electromagnetic radiation. 
E)  The radiation from the stars will continuously heat up the universe. 
A)  The universe will end in a giant inferno. 
B)  The universe will reach thermal equilibrium. 
C)  Some day the sun will explode and we will all burn. 
D)  Some day the sun will cease to provide electromagnetic radiation. 
E)  The radiation from the stars will continuously heat up the universe.

Question 5

The ocean thermal energy conversion project uses the surface water near tropical islands with a temperature of 20.0°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 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 6

An air conditioner with a coefficient of performance of 3.5 uses 30 kW of power. How much power is it discharging to the outdoors?

Accepted Answer

A)  30 kW 
B)  75 kW 
C)  105 kW 
D)  135 kW 
E)  210 kW 
A)  30 kW 
B)  75 kW 
C)  105 kW 
D)  135 kW 
E)  210 kW

Question 7

A gas expands from an initial volume of 30.0 L to a final volume of 65.0 L at a constant pressure of 110 kPa. How much work is done by the gas?

Accepted Answer

A)  3.85 kJ 
B)  10.4 kJ 
C)  3850 kJ 
D)  10.4 MJ 
E)  3.85 MJ 
A)  3.85 kJ 
B)  10.4 kJ 
C)  3850 kJ 
D)  10.4 MJ 
E)  3.85 MJ

Question 8

In a given reversible process, the temperature of an ideal gas is kept constant as the gas is compressed to a smaller volume. Select the true statement from among the following:

Accepted Answer

A)  The gas must absorb heat from its surroundings. 
B)  The gas must release heat to its surroundings. 
C)  The pressure of the gas also stays constant. 
D)  The process is adiabatic. 
E)  It is impossible to predict on the basis of this data. 
A)  The gas must absorb heat from its surroundings. 
B)  The gas must release heat to its surroundings. 
C)  The pressure of the gas also stays constant. 
D)  The process is adiabatic. 
E)  It is impossible to predict on the basis of this data.

Question 9

FIGURE 18-3  
-An ideal gas undergoes the process a→b→c→a shown in Figure 18-3. Pa = Pc = 360.0 kPa, Vb = Vc = 68.00 L, Va = 35.00 L, and Pb = 560.0 kPa. How much work is done by the system in this process?

Accepted Answer

A)  2300 J 
B)  3300 J 
C)  2800 J 
D)  3800 J 
E)  3000 J 
A)  2300 J 
B)  3300 J 
C)  2800 J 
D)  3800 J 
E)  3000 J

Question 10

If a thermometer measures the temperature of two objects as being equal, you can conclude that the objects will be in thermal equilibrium if they are brought into thermal contact.

Accepted Answer

A) True 
 B)False

Question 11

On a cold winter day, the outside temperature is -20°C and the inside temperature is maintained at 20°C. There is a net heat 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?

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 12

A 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)  922 J 
B)  833 J 
C)  744 J 
D)  3735 J 
E)  5422 J 
A)  922 J 
B)  833 J 
C)  744 J 
D)  3735 J 
E)  5422 J

Question 13

An ideal monatomic gas undergoes a reversible expansion to 1.5 times its original volume. In which of these processes does the gas have the largest loss of internal energy?

Accepted Answer

A)  at constant pressure 
B)  if the pressure increases in proportion to the volume 
C)  if the pressure decreases in proportion to the volume 
D)  at constant temperature 
E)  adiabatically 
A)  at constant pressure 
B)  if the pressure increases in proportion to the volume 
C)  if the pressure decreases in proportion to the volume 
D)  at constant temperature 
E)  adiabatically

Question 14

FIGURE 18-2  
-Referring to Figure 18-2, a substance carried from point A to B absorbs 50. J and finds its internal energy has increased by 20. J. Going from B to C the internal energy decreases by 5. Joules.
(a) How much work was done from A to B?
(b) How much heat was absorbed from B to C?
(c) How much work was done going from B to C?

Accepted Answer

(a)30.J
(b

Question 15

What is the change of entropy of water (Lf = 0.333 MJ/kg, Lv = 2.26 MJ/kg) when 450. grams of water:
(a) changes from liquid to steam?
(b) changes from ice to liquid?

Accepted Answer

(a)2.73 kJ

Question 16

One of the most efficient engines built so far has the following characteristics:
 combustion chamber temperature = 1900°C; exhaust temperature = 430°C. 7.0 × 109 cal of fuel produces
1.4 × 1010 J of work in one hour. What is the power output, in hp, of this engine?

Accepted Answer

Question 17

In the first law of thermodynamics, W is the work done on the system, that is, W is positive if work is done on the system.

Accepted Answer

A) True 
 B)False

Question 18

A certain engine extracts 1300 J of heat from a hot temperature reservoir and discharges 700 J of heat to a cold temperature reservoir. What is the efficiency of this engine?

Accepted Answer

A)  46% 
B)  54% 
C)  86% 
D)  27% 
E)  13% 
A)  46% 
B)  54% 
C)  86% 
D)  27% 
E)  13%

Question 19

How much heat is required to raise the temperature of 2 moles of an ideal monatomic gas by 10 C° at constant volume?

Accepted Answer

A)  249 J 
B)  416 J 
C)  208 J 
D)  200 J 
E)  125 J 
A)  249 J 
B)  416 J 
C)  208 J 
D)  200 J 
E)  125 J

Question 20

On a cold winter day, the outside temperature is -20°C and the inside temperature is maintained at 20°C. There is a net heat flow to the outside through the walls, roof, etc., of 25 kW. At what rate is the air outside the house gaining entropy as a result of this process?

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

Exam 18: The Laws of Thermodynamics

Order in one part of the universe can only be produced at the expense of disorder in another part.

A heat engine operating at maximum efficiency has an efficiency of 35.0%. The temperature of the hot reservoir is 700 K. What is the temperature of the cold reservoir?

A refrigerator has a COP of 2.5. If it removes 7.7 MJ of heat in 25. minutes, (a) what is the minimum power motor to operate the refrigerator? (b) what is its efficiency if it were a reversible engine?

What is meant by "the heat death of the universe"?

An air conditioner with a coefficient of performance of 3.5 uses 30 kW of power. How much power is it discharging to the outdoors?

A gas expands from an initial volume of 30.0 L to a final volume of 65.0 L at a constant pressure of 110 kPa. How much work is done by the gas?

In a given reversible process, the temperature of an ideal gas is kept constant as the gas is compressed to a smaller volume. Select the true statement from among the following:

FIGURE 18-3 -An ideal gas undergoes the process a→b→c→a shown in Figure 18-3. Pa = Pc = 360.0 kPa, Vb = Vc = 68.00 L, Va = 35.00 L, and Pb = 560.0 kPa. How much work is done by the system in this process?

If a thermometer measures the temperature of two objects as being equal, you can conclude that the objects will be in thermal equilibrium if they are brought into thermal contact.

On a cold winter day, the outside temperature is -20°C and the inside temperature is maintained at 20°C. There is a net heat 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?

A 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?

An ideal monatomic gas undergoes a reversible expansion to 1.5 times its original volume. In which of these processes does the gas have the largest loss of internal energy?

What is the change of entropy of water (Lf = 0.333 MJ/kg, Lv = 2.26 MJ/kg) when 450. grams of water: (a) changes from liquid to steam? (b) changes from ice to liquid?

One of the most efficient engines built so far has the following characteristics: combustion chamber temperature = 1900°C; exhaust temperature = 430°C. 7.0 × 109 cal of fuel produces 1.4 × 1010 J of work in one hour. What is the power output, in hp, of this engine?

In the first law of thermodynamics, W is the work done on the system, that is, W is positive if work is done on the system.

A certain engine extracts 1300 J of heat from a hot temperature reservoir and discharges 700 J of heat to a cold temperature reservoir. What is the efficiency of this engine?

How much heat is required to raise the temperature of 2 moles of an ideal monatomic gas by 10 C° at constant volume?

On a cold winter day, the outside temperature is -20°C and the inside temperature is maintained at 20°C. There is a net heat flow to the outside through the walls, roof, etc., of 25 kW. At what rate is the air outside the house gaining entropy as a result of this process?

Introduction to Physics

One-Dimensional Kinematics

Vectors in Physics

Two-Dimensional Kinematics

Newtons Laws of Motion

Applications of Newtons Laws

Work and Kinetic Energy

Potential Energy and Conservation of Energy

Linear Momentum and Collisions

Rotational Kinematics and Energy

Rotational Dynamics and Static Equilibrium

Gravity

Oscillations About Equilibrium

Waves and Sound

Fluids

Temperature and Heat

Phases and Phase Changes

Electric Charges, Forces, and Fields

Electric Potential and Electric Potential Energy

Electric Current and Direct-Current Circuits

Magnetism

Magnetic Flux and Faradays Law of Induction

Alternating-Current Circuits

Electromagnetic Waves

Geometrical Optics

Optical Instruments

Physical Optics: Interference and Diffraction

Relativity

Quantum Physics

Atomic Physics

Nuclear Physics and Nuclear Radiation

Filters

FIGURE 18-3 -An ideal gas undergoes the process a→b→c→a shown in Figure 18-3. P_a = P_c = 360.0 kPa, V_b = V_c = 68.00 L, V_a = 35.00 L, and P_b = 560.0 kPa. How much work is done by the system in this process?

What is the change of entropy of water (L_f = 0.333 MJ/kg, L_v= 2.26 MJ/kg) when 450. grams of water: (a) changes from liquid to steam? (b) changes from ice to liquid?

One of the most efficient engines built so far has the following characteristics: combustion chamber temperature = 1900°C; exhaust temperature = 430°C. 7.0 × 10⁹ cal of fuel produces 1.4 × 10¹⁰ J of work in one hour. What is the power output, in hp, of this engine?