What does the principle of conservation of energy state?

The principle of conservation of energy states that the total amount of energy in a closed system remains constant over time. This means that energy can neither be created nor destroyed but can only change forms. In a closed system, when one type of energy decreases, another type must increase by an equivalent amount to keep the total energy constant. For example, potential energy can be converted into kinetic energy, thermal energy can increase due to friction, or chemical energy can be transformed into thermal energy during combustion.

This principle is foundational in physics and applies to various processes, including mechanical systems, thermal systems, and chemical reactions. It emphasizes the concept that although energy may change from one form to another, the total energy before and after an event remains the same within a closed system.