Exam-style question
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What is the primary difference between expansion work and compression work in thermodynamic processes?.
- A.Expansion work occurs when a gas expands against external pressure.
- B.Compression work occurs when a gas is compressed by external pressure.
- C.Expansion work results in energy being added to the system.
- D.Compression work results in energy being removed from the system.
Model answer
What a good answer should say
- Expansion work occurs when a gas expands against external pressure.
Explanation
Why this works
Expansion work is defined as the work done by a gas when it expands against an external pressure, while compression work is the work done on a gas when it is compressed. The key difference is that expansion work involves the gas doing work on the surroundings, whereas compression work involves the surroundings doing work on the gas.
Expansion work applies in scenarios where gases are allowed to do work, such as in engines, while compression work applies when gases are being compressed, such as in refrigeration systems. Therefore, the correct option is that expansion work occurs when a gas expands against external pressure.
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