Which statement best explains the law of conservation of energy?

• A. Energy cannot be created or destroyed; it is transformed or transferred; e.g., a falling leaf's potential becomes kinetic.
• B. Energy is always created when doing work.
• C. Energy can be created from nothing in mechanical systems.
• D. Energy is only conserved in idealized scenarios; in real life it's not conserved.

Answer: (A)

Energy cannot be created or destroyed; it can only be transformed from one form to another or transferred between objects. This means a falling leaf starts with gravitational potential energy at the top and, as it falls, that energy becomes kinetic energy, while some energy also converts to heat and sound due to air resistance. If you account for all forms of energy in the system, the total energy remains the same, even though its form changes. The other statements imply energy appears or disappears or that conservation only applies in ideal scenarios, which isn’t how energy works in reality.