Physics: Energy Is Not Lost — It Is Transformed.

Energy can’t be created or destroyed—only transformed from one form to another. That’s the law of conservation of energy, and it governs everything from a falling apple to a roller coaster racing down a track. In this post, we’ll explore how gravitational potential energy (GPE = mgh) becomes kinetic energy (KE = ½mv²) as an object descends, and why that transformation is never perfectly efficient. The key twist is that mechanical energy isn’t the whole story. As the roller coaster car moves, friction between wheels and track, plus air resistance, convert some of its kinetic and potential energy into heat and sound. That’s why the car can’t climb back to its original height—not because energy vanished, but because it spread into less useful forms. The total energy (mechanical + heat + sound) stays constant, even though the “usable” mechanical share shrinks. Understanding this distinction—between energy being lost versus dissipated—is central to mastering energy conservation in real-world systems.