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.