- plural noun a set of laws of physics which state that energy, mass, angular momentum and other physical properties of systems are unvarying
- (written as Conservation Laws)Laws of Physics providing that energy, mass, angular momentum and other physical properties of systems are unvarying. Thus energy is not destroyed by use – merely degraded into useless forms – and a car which wears out weighs as much as a new one until pieces start to fall off. Alterations in the amount of mass, energy or angular momentum in a system show that the system itself is not fully closed, as when atmospheric drag slows a satellite and causes it to reenter the Earth’s atmosphere. In relativistic systems, like a star or a nuclear power station, matter can be changed into energy, but even then the total amount of both resources is conserved.