關於絕熱膨漲的問題 - Ans.fyi 參考答案

關於絕熱膨漲的問題

Atheist

2011-11-16 2:56 am

絕熱膨脹是與外界沒有熱量交換的膨脹過程。過程是氣體對外界做功，因為氣體膨脹。
假設我把活塞拉開，管內氣體迅速膨漲，我和氣體都有對活塞做功，不是嗎？為什麼只有氣體對外界做功？

Adiabatic expansion is a process where no heat is transferred from one system to another. Now when a gas is allowed to expanse quickly, work is done by the gas but not done by both the gas and me, why?

更新1:

它指的究竟是「氣體它自己膨漲」還是「我把活塞拉開導致氣體膨漲」？

更新2:

如果它指的是「氣體它自己膨漲」的話，現實中真的有「不把氣體加熱並且能讓氣體自己膨漲」這樣的情況嗎？

回答 (1)

天同

2011-11-16 4:32 am

✔ 最佳答案

Q: 它指的究竟是「氣體它自己膨漲」還是「我把活塞拉開導致氣體膨漲」？

The gas does work when it expands by its own.

If you expand the gs by lifting off a piston, the gas, in fact, expands "into a vacuum". Under such situation, the gas does no work.

Q: 如果它指的是「氣體它自己膨漲」的話，現實中真的有「不把氣體加熱並且能讓氣體自己膨漲」這樣的情況嗎？

Yes, if the external pressure is reducedsuddenly, the gas expands by itself. Examples are numerous, like rapid depressurization in a "pressure chamber", or a deep-sea diver rapidly rising to the surface, air in his lungs expands by its own.

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