As an object falls freely near the Earth's surface, its speed increases. This energy change represents which energy transformation?

• A. Potential energy to kinetic energy
• B. Kinetic energy to friction
• C. Friction to kinetic energy
• D. Kinetic energy to potential energy

Answer: (A)

When gravity acts on a falling object, it does work on it, converting gravitational potential energy into kinetic energy. Near Earth's surface, potential energy is mgh and kinetic energy is (1/2)mv^2. As the height h decreases during the fall, potential energy decreases while the speed increases, so the lost potential energy appears as increased kinetic energy. If air resistance is negligible, mechanical energy is conserved, and the decrease in potential energy exactly matches the increase in kinetic energy. In real conditions with some drag, some energy also goes into heating the air and object, but the primary transformation the motion demonstrates is gravitational potential energy turning into kinetic energy.