The stored energy in water behind a dam turns into which type of energy as it flows downhill?

• A. Potential Energy
• B. Kinetic Energy
• C. Thermal Energy
• D. Chemical Energy

Answer: (B)

Water behind a dam has gravitational potential energy because of its height above the downstream level. When released, gravity pulls it downward, causing acceleration. The height (potential energy) decreases while the energy of motion (kinetic energy) increases, so the stored energy is transformed into kinetic energy as the water flows downhill. If losses like friction are ignored, all the initial potential energy mgh would become kinetic energy (½mv²). In real systems some energy becomes heat or is captured by turbines, but the energy type associated with the downhill flow itself is kinetic energy.