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Physics Chapter 8 : Topic 20
Energy Degradation in Natural Processes
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Energy degradation means:
Reasoning: Energy is conserved, but during natural processes it becomes more dispersed and less useful.
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According to the second law of thermodynamics, natural processes:
Reasoning: Natural processes increase entropy, causing energy to become less available for useful work.
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The degradation of energy during natural processes is related to:
Reasoning: Entropy increase represents spreading of energy and reduction in its usefulness.
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When energy is degraded, the total amount of energy:
Reasoning: The first law states that energy cannot be created or destroyed.
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Which statement best describes energy degradation?
Reasoning: Energy remains present but becomes more randomly distributed.
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Friction causes energy degradation because:
Reasoning: Friction converts useful mechanical energy into dispersed heat.
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A moving car eventually stops due to friction because:
Reasoning: The car’s mechanical energy becomes heat energy spread into the surroundings.
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Cooling of a hot object in a room is an example of:
Reasoning: Heat spreads into the surroundings, reducing its ability to perform useful work.
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Heat transfer from a hot body to a cold body causes:
Reasoning: Energy becomes more evenly distributed, making it less useful.
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Burning fuel in an engine degrades energy because:
Reasoning: Combustion converts concentrated chemical energy into less organized thermal energy.
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Which form of energy is considered more useful?
Reasoning: Electrical energy is highly organized and can easily be converted into useful work.
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Waste heat from machines is called degraded energy because:
Reasoning: Low-temperature heat is difficult to convert into useful work.
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A power plant releases waste heat into the environment because:
Reasoning: The second law limits the efficiency of heat engines.
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A heat engine cannot convert all supplied heat into work because:
Reasoning: The second law requires rejection of heat to a lower-temperature reservoir.
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Increasing entropy during a process indicates:
Reasoning: Entropy increase represents spreading of energy among more possible states.
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The second law of thermodynamics explains:
Reasoning: The second law describes the direction and efficiency limits of energy conversion.
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A natural process always tends toward:
Reasoning: Natural processes increase disorder and degrade energy quality.
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Which process shows energy degradation?
Reasoning: Friction produces irreversible energy conversion.
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In an irreversible process:
Reasoning: Irreversible processes increase disorder and reduce energy quality.
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The ultimate result of energy degradation is:
Reasoning: Energy remains conserved but becomes less available for useful purposes.
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Why does a refrigerator require electrical energy?
Reasoning: Work input is required to move heat from a colder region to a hotter region.
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Opening a refrigerator door cannot cool a room because:
Reasoning: The refrigerator releases removed heat plus electrical energy into the room.
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Solar energy reaching Earth becomes partly degraded because:
Reasoning: Energy eventually disperses as low-temperature thermal energy.
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The energy from a battery after powering a device is degraded because:
Reasoning: Some electrical energy is converted into waste heat.
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Which example represents maximum energy degradation?
Reasoning: Friction is an irreversible process producing entropy.
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A machine receives $\mathbf{2000\ J}$ energy and produces $\mathbf{1500\ J}$ useful work. The remaining energy is:
Reasoning: The remaining $\mathbf{500\ J}$ exists mainly as waste heat.
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If entropy of a system increases, the amount of useful energy:
Reasoning: Higher entropy means lower energy availability for work.
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A reversible process is considered ideal because:
Reasoning: Reversible processes produce no entropy and preserve energy quality.
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Which statement is correct?
Reasoning: Energy quantity remains constant, but energy quality decreases.
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The best explanation of “energy is degraded during all natural processes” is:
Reasoning: Natural irreversible processes increase entropy and reduce the usefulness of energy.
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