The Law of Conservation of Energy says within a closed system, energy can neither be created nor destroyed.
The total energy within a system, for example weights being dropped on a floor, always remain constant. Upon impact, all of the energy from the falling weight gets redistributed in the following 3 ways:
- Reflected back into the falling object: as seen when a weight rebounds back up.
- Transmitted through the flooring into adjacent areas as sound and vibrational energy.
- Absorbed by the flooring