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I have been having an https://www.physicsforums.com/showthread.php?t=145867&page=3" with Morbius on the Nuclear Engineering board about whether the energy released in fission is from the nuclear force or the coulomb force. This quote from Feynman suggests that the energy is from the coulomb force:
Morbius has persuaded me that Feynman overstated and oversimplified things. Also Feynman's description of the uranium nucleus is really not accurate (since U-235 or 238 are both quite stable). Morbius maintains that, while some of the energy is from the coulomb potential, most of the energy in fission comes from the nuclear energy produced when a neutron is absorbed by the nucleus.
My question is this: where do the energetic neutrons come from in fission? If the energy comes from the nuclear force yanking the neutron in and giving it such tremendous energy, how is it that this energy is sufficient to not only free more than one other neutron from the nucleus (which would have to overcome their binding energies which would be at least as great as the binding energy ofthe incoming neutron) but to also give the free neutrons more kinetic energy than the incoming neutron had?
AM
Richard Feynman said:" There is another question: "What holds the nucleus together?" In a nucleus there are several protons, all of which are positive. Why don't they push themselves apart? It turns out that nuclei there are, in addition to electrical forces, nonelectrical forces, called nuclear forces, which are greater than the electrical forces and which are able to hold the protons together in spite of the electrical repulsion. The nuclear forces, however, have a short range - their force falls off much more rapidly than 1/r2. And this has an important consequence. If a nucleus has too many protons in it, it gets too big, and will not stay together. An example is uranium, with 92 protons. The nuclear forces act mainly between each proton (or neutron) and its nearest neighbor, while the electrical forces act over larger distances, giving a repulsion between each proton and all of the others in the nucleus. The more protons in a nucleus, the stronger is the electrical repulsion, until, as in the case of uranium, the balance is so delicate that the nucleus is almost ready to fly apart from the repulsive electrical force. If such a nucleus is just "tapped" lightly (as can be done by sending in a slow neutron), it breaks into two pieces, each with positive charge, and these pieces fly apart by electrical reuplsion. The energy which is liberated is the energy of the atomic bomb. The energy is usually called "nuclear" energy, but it is really "electrical" energy released when electrical forces have overcome the attractive nuclear forces.
Morbius has persuaded me that Feynman overstated and oversimplified things. Also Feynman's description of the uranium nucleus is really not accurate (since U-235 or 238 are both quite stable). Morbius maintains that, while some of the energy is from the coulomb potential, most of the energy in fission comes from the nuclear energy produced when a neutron is absorbed by the nucleus.
My question is this: where do the energetic neutrons come from in fission? If the energy comes from the nuclear force yanking the neutron in and giving it such tremendous energy, how is it that this energy is sufficient to not only free more than one other neutron from the nucleus (which would have to overcome their binding energies which would be at least as great as the binding energy ofthe incoming neutron) but to also give the free neutrons more kinetic energy than the incoming neutron had?
AM
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