what is the law of conservation of energy?

The law of conservation of energy states that energy can neither be created nor destroyed; it can only be transformed from one form to another. This means that the total energy within an isolated system remains constant over time. For example, potential energy can convert into kinetic energy and vice versa, but the total amount of energy stays the same. Even when energy seems to disappear, it is actually converted into other forms like thermal energy due to friction or other non-conservative forces. This principle is fundamental in physics and is also expressed as the first law of thermodynamics.