What does the first law of thermodynamics state?

The first law of thermodynamics, often referred to as the law of energy conservation, fundamentally states that energy cannot be created or destroyed in an isolated system. Instead, energy can only be transformed from one form to another. This means that the total energy within a closed system remains constant, though it can change forms, such as from kinetic energy to potential energy or from thermal energy to mechanical work.

This principle is essential for understanding many physical processes, such as engines, refrigerators, and various biological systems, where energy transformations are a fundamental aspect of their operation. It highlights the interconnectedness of different types of energy and serves as a foundation for the principles of thermodynamics as a whole.