i wanna to know some application or phenomena of 1st law of thermodynamics?
The first law of thermodynamics, like any law of physics (eg. Newton's laws of motion) is simply a statement of how nature behaves.
The first law of thermodynamics is followed in the operation of any thermodynamic device, such as a steam engine. In one complete cycle, the flow of heat into the engine minus the heat flow out of the engine is equal to the work done by the engine.
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