Why does fusion release energy?

Answer 1

Nuclear fusion releases energy, because the total mass is decreasing, as nuclear fusion is occurring. The mass of nucleus 3 is less than that of nuclei 1 and 2 combined. This '' lost" mass is converted into energy, this in accordance with Einstein's famous equation of mass-energy equivalence: E=mc2

Answer 2

This is related to the fairly strong attractions between nucleons (protons and neutrons), through a force that is called, precisely, the "strong force". In other words, before the nuclear fusion the energy is stored as a kind of potential energy. This is later converted to another type of energy.

Answer 3

Nuclear fusion is the "combining" or fusion of lighter atomic nuclei into heavier ones. In this process, when the lighter nuclei fuse, they move to a lower total nuclear energy state, and the "extra" energy is released in the process. That's why nuclear fusion reactions can be so devastating when they occur. Lots and lots of energy can be released. The sun is a giant nuclear fusion machine, and we might take a peek at it. Our sun is burning (fusing) hydrogen into helium. Later in its life, it will fuse helium into heavier elements, and those into yet heavier elements. This falls under the category of stellar nucleosynthesis. But there's a catch. The nuclear fusion reaction that results in the creation of iron is the last one that releases energy in the fusion process. Fusing iron into heavier elements requires that energy be put into the fusion reaction. And this is why stars die when they have turned largely to iron. The only way the trans-iron elements can be created is in a supernova. Links can be found below to check facts and learn more.