Physics Of Everyday Phenomena (9th Edition) A Conceptual Introduction to Physics – W. Thomas
Chapter 11 Heat Engines and the Second Law of Thermodynamics
1) The second law of thermodynamics says that the total amount of entropy, or randomness, in the universe cannot decrease. However, we see all around us objects that become more ordered—for example, the development of a biological organism or water that freezes. The decrease in entropy, or randomness, in such cases does not violate the second law because
A) energy must be removed.
B) energy must be added.
C) there is always a greater increase in entropy somewhere else.
D) water and living things do not have entropy.
Answer: C
Difficulty: 1 Easy
Topic: The second law of thermodynamics
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual
Accessibility: Keyboard Navigation
2) Why couldn’t you use an electric motor to turn an electrical generator that in turn provides the electrical energy for the motor?
A) No energy converter is 100% efficient
B) Yes, you can do this
C) Motors require AC and generators produce DC
Answer: A
Difficulty: 1 Easy
Topic: Perpetual motion and energy frauds
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual
Accessibility: Keyboard Navigation
3) Shown are four figures that represent the heat flow in a heat engine. The thickness of the arrows represents the amount of heat flow. TH is the high-temperature reservoir, TC is the low-temperature reservoir, QH is heat to/from TH, QC is heat to/from TC, and W is work. Which figure best represents a real heat engine?
A) A
B) B
C) C
D) D
Answer: B
Difficulty: 2 Medium
Topic: Refrigerators, heat pumps, and entropy
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Graphical; Conceptual
4) Energy added to a cyclical heat engine
A) is completely converted to external work.
B) is converted to work and to waste heat.
C) is used to generate work that is greater than the added energy.
D) is converted to increased internal energy in the engine plus external work.
Answer: B
Difficulty: 1 Easy
Topic: Heat engines; Refrigerators, heat pumps, and entropy
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual
Accessibility: Keyboard Navigation
5) The primary function of any heat engine is to
A) create a large amount of energy from a small amount of heat.
B) create heat.
C) convert heat into work.
D) destroy energy and replace it with work.
Answer: C
Difficulty: 1 Easy
Topic: Heat engines
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual; Definition
Accessibility: Keyboard Navigation
6) The work performed by a heat engine
A) equals the heat energy exhausted from the engine.
B) equals the heat energy entering the engine.
C) equals the change in the internal energy of the engine.
D) equals the net heat flow into the engine.
Answer: D
Difficulty: 2 Medium
Topic: Heat engines
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual
Accessibility: Keyboard Navigation
7) The change in internal energy during one complete cycle of a heat engine
A) equals zero.
B) equals the net heat flow into the engine.
C) equals the heat energy exhausted from the engine.
D) equals the heat energy entering the engine.
Answer: A
Difficulty: 1 Easy
Topic: Heat engines
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual
Accessibility: Keyboard Navigation
8) One important feature of the Carnot cycle is that it
A) maximizes the entropy of a heat engine operating between two temperatures.
B) specifies the operating temperatures of any heat engine.
C) converts all of the heat flowing into an engine to work.
D) predicts the maximum efficiency of a heat engine operating between two temperatures.
Answer: D
Difficulty: 1 Easy
Topic: The second law of thermodynamics
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual; Definition
Accessibility: Keyboard Navigation
9) The efficiency of an engine can be defined as the
A) ratio of work done to energy input.
B) total amount of work performed.
C) ratio of work done to energy exhausted.
D) ratio of heat exhausted to heat intake.
Answer: A
Difficulty: 1 Easy
Topic: Heat engines
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual; Definition
Accessibility: Keyboard Navigation
10) If a Carnot heat engine is run in reverse, it becomes
A) a heat engine with the smallest possible efficiency.
B) an engine that has a negative efficiency.
C) a refrigerator.
D) nothing. It can’t be run in reverse because to do so would violate the second law of thermodynamics.
Answer: C
Difficulty: 1 Easy
Topic: Refrigerators, heat pumps, and entropy
Chapter: 11 Heat Engines and the Second Law of Thermodynamics
Type: Conceptual; Definition
Accessibility: Keyboard Navigation
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