Explanations of fission reactions always say there’s a tremendous amount of energy released, but where is that energy? So, if an atom of u-235 was split in a complete vacuum, in what forms(s) would the released energy be?
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Imagine you had 2 strong magnets.
You face them with positive sides facing each other. They start pushing each other away at 3 inches. Using your superior strength, you shorten the distance to 1 inch but are unable to get any further.
You let the magnets go, and they fly off in opposite directions.
Repeat the exercise with 6 magnets and 2 friends. 6 magnets fly away with even greater speed. Where does the energy come from? The potential energy that comes from a repelling force and close proximity.
A uranium atom has 92 protons. Imagine you had 92 repelling magnets at a distance much smaller than a speck of dust, stuck together by the nuclear strong force
What would happen if the strong nuclear force let go? 92 protons and all the neutrons would be launched and boom. (the neutrons would also destabilize other atoms and make a chain reaction but thats a whole other eli5)
It’d be released as atomic kinetic energy, radiation and magnetic. There would also be subatomic particle kinetic energy.
Where would the atomic and subatomic kinetic energy come from? From the atom that just fissioned. The source of all that energy is the bonds that were holding the atom together in the first place.
Radiation, specifically alpha radiation, if I recall correctly, which is a particle of two protons and two neutrons. This particle has a lot of energy in it from purely kinetic energy (traveling at 5% of light speed). When the alpha particle hits something and is absorbed or otherwise interacts with the substance, that energy turns into heat.
From wikipedia:
> When a uranium nucleus fissions into two daughter nuclei fragments, about 0.1 percent of the mass of the uranium nucleus[9] appears as the fission energy of ~200 MeV. For uranium-235 (total mean fission energy 202.79 MeV[10]), typically ~169 MeV appears as the kinetic energy of the daughter nuclei, which fly apart at about 3% of the speed of light, due to Coulomb repulsion. Also, an average of 2.5 neutrons are emitted, with a mean kinetic energy per neutron of ~2 MeV (total of 4.8 MeV).[11] The fission reaction also releases ~7 MeV in prompt gamma ray photons. The latter figure means that a nuclear fission explosion or criticality accident emits about 3.5% of its energy as gamma rays, less than 2.5% of its energy as fast neutrons (total of both types of radiation ~6%), and the rest as kinetic energy of fission fragments (this appears almost immediately when the fragments impact surrounding matter, as simple heat).
So, when U235 is hit by a neutron, it splits and a tiny bit of its mass converts into energy per the famous equation of Einstein. Most of this energy is tied up in the parts of the atom formerly known as uranium getting flung *real fucking hard* away from each other and usually into other stuff. This is effectively heat. A bit of the energy goes into making some gamma frequency photons (the funny invisible light that makes your DNA say adiós) and some neutrons which can go on to hit other uranium atoms. An even smaller portion of the energy is tied up in the unstable resulting atoms and will be released over time as they decay.
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