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I can not understand the second law of thermodynamics and have trouble explaining the following questions:

1) In the tropics the water near the ocean surface is warmer than the deep water. Does the second law of thermodynamics would be violated if a machine operate between these two levels of water?

2) A car battery is connected to an electric motor is used to raise a weight. The battery remains at a constant temperature hot air getting around it. Is this a violation of the second law?

In my opinion I think that both violate the second law because Kelvin postulate. However, I can not raise my good idea, if you could explain me, they are grateful.

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None of them violate thermodynamics. For example, in 1) , a machine could do work cooling the hot source. – jinawee Mar 2 '14 at 19:42
The Sun is doing work to uphold the temperature difference in (1) and this is what drives your machine; (2) the battery has stored chemical energy: a chemical reaction is driving both the lifting of weight and the heating of air. – WetSavannaAnimal aka Rod Vance Mar 3 '14 at 23:15

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