Sample interview questions: Discuss the principles of thermodynamics in the context of environmental systems.
Sample answer:
- First Law of Thermodynamics:
- Energy cannot be created or destroyed, only transformed from one form to another.
- In environmental systems, this means that the total amount of energy in a closed system remains constant.
- Energy inputs to an environmental system include solar radiation, fossil fuel combustion, and geothermal heat.
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Energy outputs include heat loss to the atmosphere, work done by the system, and energy stored in biomass.
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Second Law of Thermodynamics:
- Entropy, a measure of disorder, always increases in a closed system.
- In environmental systems, this means that natural processes tend to increase the disorder of the system.
- For example, heat flows from hotter objects to colder objects, and pollutants tend to disperse over time.
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The second law also implies that perfect efficiency is impossible in energy conversion processes.
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Third Law of Thermodynamics:
- The entropy of a perfect crystal at absolute zero is zero.
- This law has implications for environmental systems, as it suggests that absolute zero is the only temperature at which a system can be perfectly ordered.
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In practice, environmental systems are never perfectly ordered, and thus their entropy is always greater than zero.