What does the Law of Conservation of Energy state?

The Law of Conservation of Energy states that energy can be transformed from one form to another but cannot be created or destroyed. This principle is fundamental in understanding various physical processes, such as chemical reactions, mechanical systems, and even in the realm of thermodynamics. For instance, when you ride a bicycle downhill, potential energy (due to elevation) transforms into kinetic energy (the energy of motion).

This principle explains why energy remains constant in a closed system, where the total energy before and after any process remains the same, even if it changes forms. Options that suggest energy can be created or destroyed, is always constant, or can only be lost or gained misinterpret the core idea of energy conservation by implying that energy is not a stable quantity or can somehow vanish or appear from nothing.