Science, Tech, Math › Science The Law of Conservation of Energy Defined Energy is neither created nor destroyed Share Flipboard Email Print Mmdi/Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated January 09, 2020 The law of conservation of energy is a physical law that states energy cannot be created or destroyed but may be changed from one form to another. Another way of stating this law of chemistry is to say the total energy of an isolated system remains constant or is conserved within a given frame of reference. In classical mechanics, conservation of mass and conversation of energy are considered to be two separate laws. However, in special relativity, matter may be converted into energy and vice versa, according to the famous equation E = mc2. Thus, it's more appropriate to say mass-energy is conserved. Example of Conservation of Energy If a stick of dynamite explodes, for example, the chemical energy contained within the dynamite changes into kinetic energy, heat, and light. If all this energy is added together, it will equal the starting chemical energy value. Consequence of Conservation of Energy One interesting consequence of the law of conservation of energy is that it means perpetual motion machines of the first kind are not possible. In other words, a system must have an external power supply to continuously deliver unlimited energy to its surroundings. It's also worth noting that it's not always possible to define conservation of energy because not all systems have time translation symmetry. For example, conservation of energy may not be defined for time crystals or for curved space times.