The conservation of energy is a fundamental principle in physics stating that energy cannot be created or destroyed, only transformed from one form to another. For example, when a roller coaster descends, its potential energy converts into kinetic energy, allowing it to speed up. The total energy in a closed system remains constant throughout these transformations. This principle applies to various systems, from simple machines to complex ecosystems. In renewable energy sources like solar panels, sunlight is converted into electrical energy, demonstrating how energy changes form while the total amount remains unchanged. Understanding this concept is crucial for efficient energy use and sustainability.