When one system gains energy, what happens to another system?

In the scenario where one system gains energy, it aligns with the principle of energy conservation, which states that energy cannot be created or destroyed but can only be transferred from one system to another. Hence, when one system gains energy, there must be a corresponding loss of energy in another system. This energy transfer is crucial in various physical processes, such as heat transfer or work done.

For example, if you have a heating element that warms a pot of water, the heating element gains thermal energy while the water, in turn, absorbs that energy leading to a corresponding decrease in the thermal energy of the heating source (assuming no external energy input). This principle holds true across many fields of physics, including mechanical systems, electrical systems, and thermodynamics. The understanding of this energy interplay is fundamental for analyzing physical interactions and energy exchanges.