Why does mass change into energy in an atomic explosion?

I was wondering why this happens. It seemed to me that something would need to happen in oder for this change to happen. And i didn't how smashing anther atom and splitting them would do that.





I know that the relationship is E=MC^2 , but at the same time I was wonder what the speed of light has to do with it.

Why does mass change into energy in an atomic explosion?
It doesn't quite work as simply as you explain it





If you look at the mass of a single proton and neutron, then look at the mass of a helium nucleus, you'll see that the nucleus has less mass than the mass of a single proton *2+mass of single neutron *2, implying that the nucleus now has a "binding" energy in it of E=delta-M/c^2 where delta-M is the difference in mass between the individual parts and the bound nucleus





The binding energy of the nucleus is rather huge(keep in mind that protons are all electrically positive, and in a nucleus are incredibly close. The force easily overpowering that IMMENSE repulsive force is the strong nuclear force, one of the four fundamental forces of the universe. It's basically the opposite of gravity. Gravity is weak but long ranged, the strong force is STRONG but VERY short range, just the size of the nucleus)





During nuclear fusion, two small nuclei, like helium or hydrogen, are forced together, so close that the strong nuclear force grabs hold and binds them. For small atoms, the binding energy per nucleon is smaller as they get bigger, so by increasing the size of the nuclei, the required binding energy is less, and the leftover binding energy is released. Do that to enough atoms at once and the released energy is, well, enough to level a city obviously





Now for large atoms, it's a different case. The binding energy decreases as the atom gets SMALLER(the turning point is iron-56, it has the largest binding energy per nucleon, any atoms smaller or larger have less binding energy per nucleon)





So by taking a large atom like uranium or plutonium and separating the large nucleus into smaller nuclei with lower binding energy, in the same way the excess energy is released





Pound for pound, fusion is FAR more energetic, but much harder to create a sustained controlled reaction of. We can use it in bombs, but obviously that type of reaction is unsuitable for domestic use





Addition: Also, nuclear fusion of large atoms and fission of small elements isn't energetically favorable, as dear nature likes to keep things at the lowest possible energy states. It would take more energy to fuse two large nuclei or to fission a small nuclei than you would get out, so the reaction cannot be in any way self-sustaining





ONE MORE EDIT: To answer your last part about E=mc^2, that's the equation for the rest energy of a mass





This comes from special relativity. You may know from a basic physics class that F=dp/dt. All good and well when p=mv, but in relativity it scales up as relative velocity increases, so it's really p=mv*(1-v^2/c^2)^(-1/2), which when v%26lt;%26lt;%26lt;%26lt;%26lt;c, like it normally is, reduces to just p=mv





Using the work energy theorem, you can derive an expression for the total energy of an object, you use the work energy theorem to find KE=mc^2(1-v^2/c^2)^(-1/2)-mc^2, so you get that expression with the square root = KE+mc^2, KE is the energy from motion, implying that even without motion the mass has energy mc^2, but it's not the simplest thing in the world and I don't remember offhand quite how to proceed. You'd take dp/dt and integrate from 0 to s, remembering that a=dv/ds and v=ds/dt
Reply:Strictly speaking, mass is not turned into energy - at least, mass attributed to matter is not.





The nucleons in the nucleus (protons and neutrons) are held together by what is called the residual strong nuclear force. The strong force actually acts between the quarks that make up each nucleon to hold them together, but because protons and neutrons are not point particles there is a residual element to this for nearby nucleons because they will "see" some quarks of the neighbouring nucleon closer than others.





The amount of energy this leads to holding the nucleons together rises as nuclei increase in size to iron, then falls again. So if you take a large nucleus and break it into two small ones, the two smallones will be more tightly bound than the large one - and the spare energy will be released.





Now actually because there is an equivalence between mass and energy (E = mc^2) then from outside the nucleus this difference in energy is observed as a difference in mass.
Reply:Because mass and energy are simply different forms of the same thing. Space and time are also different forms of the same thing. (Kinda like ice and steam are different forms of the same thing, but with very different characteristics).


Spend a couple of years studying Special Relativity, the ideas of mass-energy and space-time, and it may begin to all make sense.





HTH,


Doug
Reply:the same thing happens in many other energy transfer processes. it is only that the energies involved in nuclear reactions are so large, as a fraction of the total mass energy, that mass changes are easily measurable. it is not the case that something different is happening, only with nuclear reactions. perhaps you might be thinking that mass is a simple property of particles in isolation - evidently it isn't.
Reply:No, the speed of light will not change mass into energy.


I'm no scientist, But I would logically say..


All the energy that is caused during an atomic explosion dissolves the mass and fuses it with itself.





Probably not on the right path, but a guess.