Definitions for "Law of conservation of energy"
The amount of energy within the universe is constant; energy cannot be created or destroyed, only transformed.
A principle that cannot be violated by any physical process, it states that; energy can neither be created nor destroyed, it only changes in form.
energy is neither created nor destroyed in an ordinary chemical or physical process; energy is conserved in all changes except nuclear reactions.
Keywords:  thermodynamics, first, see
See first law of thermodynamics.