The law of conservation of matter and energy states that within a closed system, the total amount of matter and energy remains constant over time. This means that matter cannot be created or destroyed; it can only change forms. Similarly, energy can neither be created nor destroyed but can change from one form to another (for example, from kinetic energy to potential energy).
The law of conservation of matter focuses solely on matter, asserting that the mass of an isolated system will remain constant despite the processes occurring within that system. For instance, when a chemical reaction occurs, the total mass of the reactants will equal the total mass of the products.
On the other hand, the law of conservation of energy highlights the constancy of energy in a closed system. It asserts that the total energy remains the same before and after a process, even though energy may transform from one form to another, such as heat, light, or mechanical energy.
In summary, the law of conservation of matter and energy combines the principles of both laws into a single statement, emphasizing the interrelation between matter and energy, while each of the other two laws deals with only one aspect: matter or energy individually. Understanding these laws helps explain how physical processes operate without loss or gain of total mass or energy in a closed system.