A

David

Darling

conservation law

A conservation law is a law which states that some property of a closed system is unaltered by changes in that system. Among the most important are the law of conservation of mass and energy and the law of conservation of momentum.

 


Law of conservation of mass and energy

The law of conservation of mass and energy is a principle, resulting from Einstein's special theory of relativity, which combines the separate laws of conservation of mass and of energy. The law of conservation of mass (or matter) states that in any system matter cannot be created or destroyed and the law of conservation of energy states that in any system energy cannot be created or destroyed. These laws are now seen to be approximations which can only be applied to systems not involving nuclear reactions or speeds approaching the speed of light. The general principle of the conservation of mass and energy, which is of universal applicability, is based upon the mass-energy relationship.

 


Law of conservation of momentum

Conservation of momentum is a fundamental law of motion, equivalent to Newton's laws: in a system of bodies, the vector sum of all momenta cannot change due to any internal interactions.