----------------------------------- person Thu Nov 24, 2005 5:45 pm nuclear fission+fusion ----------------------------------- according to my teacher, nuclear fission creates a lot of energy, yet nuclear fusion creates more energy and this doesnt make much sense to me considering that they seem to be the exact opposite of eachother...can anyone explain? ----------------------------------- rdrake Thu Nov 24, 2005 7:04 pm ----------------------------------- Nuclear fission is when a neutron smashes into a large atom and breaks it apart. This requires no extermal energy as the neutron has all the energy the reaction needs. This neutron collision releases another few neutrons which repeats the process. Nuclear fusion on the other hand is when the smaller atoms combine to produce a larger one. The atoms repel each other so they must be travelling at very high speeds in order to get close enough to combine. Basically, nuclear fission is easier to perform and happens quicker, while nuclear fusion takes high speeds in order to happen. This is due to the positive nature of the atoms. They repel and it takes more to combine them. ----------------------------------- person Thu Nov 24, 2005 7:07 pm ----------------------------------- i know all that, but im talking about like why do tehy both release energy when they seem to be opposite to eachother ----------------------------------- 1of42 Thu Nov 24, 2005 7:36 pm ----------------------------------- Because fission is tapping into the electromagnetic force for its energy, while fusion is tapping into the strong nuclear force - both release energy, with the latter being MUCH stronger. ----------------------------------- Tony Thu Nov 24, 2005 7:38 pm ----------------------------------- Wikipedia is great. In short, If two light nuclei come close enough to each other, they may fuse to form a single nucleus with a slightly smaller mass than the sum of their original masses. The difference in mass is released as energy according to Einstein's relationship E = mc². (If the two nuclei are too heavy, then the resulting fusion product will be heavier than the reactants, and the reaction requires the addition of energy to convert into the additional mass; in this case the reverse process of nuclear fission will release energy which can be used, for example, in nuclear reactors or bombs.) ----------------------------------- rdrake Thu Nov 24, 2005 7:40 pm ----------------------------------- When the nucleus splits in nuclear fission, energy is released. In nuclear fusion, there is energy released because the helium nucleus has a much larger binding energy than deuterium/tritium. Energy is absorbed by nuclear fusion if the product element is further down on the periodic table than iron, so anything with an atomic number of about 55/56 (I forget) and up will produce energy. If you have the textbook Physics 12 by McGraw-Hill Ryerson, then you can find all of this information on pages 566-568. ----------------------------------- Andy Thu Nov 24, 2005 8:49 pm ----------------------------------- the key is to notice that not all elements are fissiable and fusable. Lead is the cut off line for fission and Iron is the cut off line for fusion, so you cant simply split an atom then fuse it back and then split it again forever, also, remember that at each step, mass is lost so they're not reverse reactions. ----------------------------------- Tony Thu Nov 24, 2005 8:53 pm ----------------------------------- remember that at each step, mass is lost so they're not reverse reactions. Actually if you fuse two elements heavier than Iron, mass is gained :wink: You loose energy though. ----------------------------------- person Fri Nov 25, 2005 6:32 pm ----------------------------------- If two light nuclei come close enough to each other, they may fuse to form a single nucleus with a slightly smaller mass but in the chemical formulas of fusion, the mass on the left is teh same as the mass on the right ----------------------------------- rdrake Fri Nov 25, 2005 10:31 pm ----------------------------------- If two light nuclei come close enough to each other, they may fuse to form a single nucleus with a slightly smaller mass but in the chemical formulas of fusion, the mass on the left is teh same as the mass on the rightIn fusion, mass is often lost between the products and reactants. This is called the mass defect and is important. We use the formula E=mc^2 to determine the energy which is produced, based on the mass defect. This loss of mass is where the energy comes from, as the mass is converted into useful energy. ----------------------------------- Andy Sat Nov 26, 2005 1:54 am ----------------------------------- remember that at each step, mass is lost so they're not reverse reactions. Actually if you fuse two elements heavier than Iron, mass is gained :wink: You loose energy though. except tony, you cant fuse elements heavier than iron together ----------------------------------- Tony Sat Nov 26, 2005 2:36 am ----------------------------------- The fusion of two nuclei to produce a nucleus lighter than iron or nickel generally gives off energy while the fusion of nuclei heavier than them absorbs energy. Perhaps you should edit the article ----------------------------------- rdrake Sat Nov 26, 2005 9:18 am ----------------------------------- except tony, you cant fuse elements heavier than iron togetherYou can, but then energy is absorbed, not released. ----------------------------------- Paul Sat Nov 26, 2005 12:33 pm ----------------------------------- I dunno if this helps, but... simply put: The sun: Fusion on a massive scale Atomic Bombs: fission They both produce energy. The advantage to fusion is that it doesn't produce all the waste products that fission does. ----------------------------------- Drakain Zeil Sat Nov 26, 2005 3:44 pm ----------------------------------- bonds hold energy, breaking them requires energy, building them gives energy. end of story. ----------------------------------- 1of42 Sat Nov 26, 2005 8:35 pm ----------------------------------- bonds hold energy, breaking them requires energy, building them gives energy. end of story. ...which explains chemical potential energy. thanks for coming out, though. ----------------------------------- Andy Mon Nov 28, 2005 8:37 pm ----------------------------------- well technically if you look at the formation equations in chemistry, its kinda similar to the binding of nucleons