Question 1

A turbine takes in 2 200-K steam and exhausts the steam at a temperature of 200 K.What is the maximum theoretical efficiency of this system?​

Accepted Answer

A) 83% 
B) 75% 
C) 91% 
D) 68% 
E) ​62% 
A) 83% 
B) 75% 
C) 91% 
D) 68% 
E) ​62%

Question 2

The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following?

Accepted Answer

A) hot reservoir temperature only 
B) cold reservoir temperature only 
C) both hot and cold reservoir temperatures 
D) None of the above choices are valid. 
A) hot reservoir temperature only 
B) cold reservoir temperature only 
C) both hot and cold reservoir temperatures 
D) None of the above choices are valid.

Question 3

A gasoline engine with an efficiency of 32.6% 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) 980 K 
B) 700 K 
C) 1 050 K 
D) 480 K 
E) ​220 K 
A) 980 K 
B) 700 K 
C) 1 050 K 
D) 480 K 
E) ​220 K

Question 4

​A gas expends to three times its original volume,and in the process no energy is transferred to the gas.What happens to the internal energy of this gas?

Accepted Answer

A) ​It increases. 
B) ​It decreases. 
C) ​It remains constant. 
D) ​Impossible to know without more information 
A) ​It increases. 
B) ​It decreases. 
C) ​It remains constant. 
D) ​Impossible to know without more information

Question 5

A person consumes 2 200 kcal/day while expending 3 200 kcal/day.In a month's time,about how much weight would this person lose if the loss were essentially all from body fat? (Body fat has an energy content of about 4 100 kcal per pound. )

Accepted Answer

A) 15 pound 
B) 22 pounds 
C) 7.3 pounds 
D) 3.7 pounds 
E) 29 pounds 
A) 15 pound 
B) 22 pounds 
C) 7.3 pounds 
D) 3.7 pounds 
E) 29 pounds

Question 6

In which system is heat usually transferred from the cooler part to the warmer part?

Accepted Answer

A) a stove as it heats up water 
B) a refrigerator that is running 
C) an electric fan that is running 
D) none of the above,because it is impossible to transfer heat in this manner 
A) a stove as it heats up water 
B) a refrigerator that is running 
C) an electric fan that is running 
D) none of the above,because it is impossible to transfer heat in this manner

Question 7

An 880-MW electric power plant has an efficiency of 20.0%.It loses its waste heat in large cooling towers.Approximately how much waste heat (in MJ)is discharged to the atmosphere per second?

Accepted Answer

A) 5 280 MJ 
B) 3 520 MJ 
C) 880 MJ 
D) 4 400 MJ 
E) 7 040 MJ 
A) 5 280 MJ 
B) 3 520 MJ 
C) 880 MJ 
D) 4 400 MJ 
E) 7 040 MJ

Question 8

​The volume of a gas changes from 0.750 m3 to 0.320 m3 at a constant pressure of 1.5 × 105 Pa.How much work is done by the gas on its environment?

Accepted Answer

A) ​4.8E+4 J 
B) ​-6.5E+4 J 
C) ​-4.8E+4 J 
D) ​6.5E+4 J 
A) ​4.8E+4 J 
B) ​-6.5E+4 J 
C) ​-4.8E+4 J 
D) ​6.5E+4 J

Question 9

An electrical power plant manages to send 90% of the heat produced in the burning of fossil fuel into the water-to-steam conversion.Of the heat carried by the steam,40% is converted to the mechanical energy of the spinning turbine.Which of the following choices best describes the overall efficiency of the heat-to-work conversion in the plant (as a percentage)?​

Accepted Answer

A) greater than 90% 
B) 65% 
C) less than 40% 
D) 40% 
E) ​90% 
A) greater than 90% 
B) 65% 
C) less than 40% 
D) 40% 
E) ​90%

Question 10

A swimmer has a metabolic rate of 600 W.How many breaths per minute should the swimmer take if her lungs take in 0.50 L of air in each breath,and the percentage of oxygen in the air is 21%?

Accepted Answer

A) 25.2 
B) 120 
C) 33.5 
D) 17.1 
A) 25.2 
B) 120 
C) 33.5 
D) 17.1

Question 11

If an ideal gas does positive work on its surroundings,we may assume,with regard to the gas

Accepted Answer

A) temperature increases. 
B) volume increases. 
C) pressure increases. 
D) internal energy decreases. 
A) temperature increases. 
B) volume increases. 
C) pressure increases. 
D) internal energy decreases.

Question 12

An adiabatic expansion refers to the fact that

Accepted Answer

A) no heat is transferred between a system and its surroundings. 
B) the pressure remains constant. 
C) the temperature remains constant. 
D) the volume remains constant. 
A) no heat is transferred between a system and its surroundings. 
B) the pressure remains constant. 
C) the temperature remains constant. 
D) the volume remains constant.

Question 13

Suppose a power plant uses a Carnot engine to generate electricity,using the atmosphere at 300 K as the low-temperature reservoir.Suppose the power plant produces 1 × 106 J of electricity with the hot reservoir at 500 K during Day One and then produces 1 × 106 J of electricity with the hot reservoir at 600 K during Day Two.The thermal pollution was

Accepted Answer

A) greatest on Day One. 
B) greatest on Day Two. 
C) the same on both days. 
D) zero on both days. 
A) greatest on Day One. 
B) greatest on Day Two. 
C) the same on both days. 
D) zero on both days.

Question 14

Of the following heat engines,which has the highest efficiency?

Accepted Answer

A) Hero's engine 
B) a Carnot engine 
C) a car's gasoline engine 
D) a truck's diesel engine 
A) Hero's engine 
B) a Carnot engine 
C) a car's gasoline engine 
D) a truck's diesel engine

Question 15

A 2-mol ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment.How much heat is received by the system?

Accepted Answer

A) −20 J 
B) zero 
C) +10 J 
D) +20 J 
E) ​−10 J 
A) −20 J 
B) zero 
C) +10 J 
D) +20 J 
E) ​−10 J

Question 16

The latent heat of vaporization of sweat is 2 430 kJ/kg at body temperature.Assuming that sweating is the only mechanism for dissipating heat,what would be the maximum sustainable metabolic rate if 75% of the energy used by the body goes into waste heat? The body can produce up to 1.5 kg of sweat per hour.​

Accepted Answer

A) ​4.9E+4 W 
B) ​4.9E+6 W 
C) ​2.2E+4 W 
D) ​1.4E+3 W 
A) ​4.9E+4 W 
B) ​4.9E+6 W 
C) ​2.2E+4 W 
D) ​1.4E+3 W

Question 17

On a PV diagram,2 curves are plotted,both starting at the same point and both ending at the same final increased volume.One curve is for an isothermal process;the other is for an adiabatic process.What does the area between these two curves represent?

Accepted Answer

A) Q absorbed by the isothermal process. 
B) W done by the adiabatic process. 
C) ΔU for the isothermal process. 
D) Neither Q,W,nor ΔU for either of the processes is represented. 
A) Q absorbed by the isothermal process. 
B) W done by the adiabatic process. 
C) ΔU for the isothermal process. 
D) Neither Q,W,nor ΔU for either of the processes is represented.

Question 18

A 2.65-kg block of ice is at STP (0°C,1 atm)while it melts completely to water.What is its change in entropy? (For ice,Lf = 3.34 × 105 J/kg)

Accepted Answer

A) zero 
B) 1 620 J/K 
C) 811 J/K 
D) 3 240 J/K 
E) 6 480 J/K 
A) zero 
B) 1 620 J/K 
C) 811 J/K 
D) 3 240 J/K 
E) 6 480 J/K

Question 19

When considering human metabolism in terms of the 1st law of thermodynamics,which of the following represents the metabolic rate?

Accepted Answer

A) ΔU / Δt 
B) ΔQ / Δt 
C) W / Δt 
D) ΔW / Δt 
A) ΔU / Δt 
B) ΔQ / Δt 
C) W / Δt 
D) ΔW / Δt

Question 20

Two cars,each of mass 2 200 kg and traveling at 14.0 m/s,undergo a head-on completely inelastic collision.What is the change in entropy of the Universe which results from this collision? Assume the ambient temperature is 20.0S1U1P1$\circ$S1S1P0C.

Accepted Answer

A) 1.47E+3 J/K 
B) 2.2E+4 J/K 
C) 7.35E+2 J/K 
D) 6.2E+5 J/K 
A) 1.47E+3 J/K 
B) 2.2E+4 J/K 
C) 7.35E+2 J/K 
D) 6.2E+5 J/K

Exam 12: The Laws of Thermodynamics

A turbine takes in 2 200-K steam and exhausts the steam at a temperature of 200 K.What is the maximum theoretical efficiency of this system?​

The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following?

A gasoline engine with an efficiency of 32.6% 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 gas expends to three times its original volume,and in the process no energy is transferred to the gas.What happens to the internal energy of this gas?

A person consumes 2 200 kcal/day while expending 3 200 kcal/day.In a month's time,about how much weight would this person lose if the loss were essentially all from body fat? (Body fat has an energy content of about 4 100 kcal per pound. )

In which system is heat usually transferred from the cooler part to the warmer part?

An 880-MW electric power plant has an efficiency of 20.0%.It loses its waste heat in large cooling towers.Approximately how much waste heat (in MJ)is discharged to the atmosphere per second?

​The volume of a gas changes from 0.750 m3 to 0.320 m3 at a constant pressure of 1.5 × 105 Pa.How much work is done by the gas on its environment?

A swimmer has a metabolic rate of 600 W.How many breaths per minute should the swimmer take if her lungs take in 0.50 L of air in each breath,and the percentage of oxygen in the air is 21%?

If an ideal gas does positive work on its surroundings,we may assume,with regard to the gas

An adiabatic expansion refers to the fact that

Of the following heat engines,which has the highest efficiency?

A 2-mol ideal gas system undergoes an adiabatic process where it expands and does 20 J of work on its environment.How much heat is received by the system?

On a PV diagram,2 curves are plotted,both starting at the same point and both ending at the same final increased volume.One curve is for an isothermal process;the other is for an adiabatic process.What does the area between these two curves represent?

A 2.65-kg block of ice is at STP (0°C,1 atm)while it melts completely to water.What is its change in entropy? (For ice,Lf = 3.34 × 105 J/kg)

When considering human metabolism in terms of the 1st law of thermodynamics,which of the following represents the metabolic rate?

Two cars,each of mass 2 200 kg and traveling at 14.0 m/s,undergo a head-on completely inelastic collision.What is the change in entropy of the Universe which results from this collision? Assume the ambient temperature is 20.0 ∘\circ∘ C.

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A turbine takes in 2 200-K steam and exhausts the steam at a temperature of 200 K.What is the maximum theoretical efficiency of this system?

A gasoline engine with an efficiency of 32.6% 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 gas expends to three times its original volume,and in the process no energy is transferred to the gas.What happens to the internal energy of this gas?

The volume of a gas changes from 0.750 m³ to 0.320 m³ at a constant pressure of 1.5 × 10⁵ Pa.How much work is done by the gas on its environment?

A 2.65-kg block of ice is at STP (0°C,1 atm)while it melts completely to water.What is its change in entropy? (For ice,L_f = 3.34 × 10⁵ J/kg)

When considering human metabolism in terms of the 1^st law of thermodynamics,which of the following represents the metabolic rate?

Two cars,each of mass 2 200 kg and traveling at 14.0 m/s,undergo a head-on completely inelastic collision.What is the change in entropy of the Universe which results from this collision? Assume the ambient temperature is 20.0^$\circ$C.