Source of extra energy? (Fusion-Fission)
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From: Uncle Al on 12 Apr 2010 10:12 Bill Bowden wrote: > > If fusion is a process of putting atoms together, and fission is a > process of breaking them apart, and both cases produce energy, then it > seems somewhat like a perpetual motion machine putting things together > and taking them apart while always producing energy. Where does the > extra energy come from? > > What am I missing? Iron, nickel, cobalt are the most stable nuclei, the ones with the greatest binding energy/nucleon. Fusion up to iron or fission down to iron are both exothermic. What you are missing is that the univserse is devoted to irony (and spiced with photodisintegration). -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz4.htm
From: PD on 12 Apr 2010 14:47 On Apr 11, 7:40 pm, Bill Bowden <wrongaddr...(a)att.net> wrote: > If fusion is a process of putting atoms together, and fission is a > process of breaking them apart, and both cases produce energy, then it > seems somewhat like a perpetual motion machine putting things together > and taking them apart while always producing energy. Where does the > extra energy come from? > > What am I missing? > > -Bill No, they are processes that operate in different domains of nuclear size. It's like a bowl with a ball in it. Put the ball on one side of the bowl and it will roll right. Put it on the other side of the ball and it will roll left.
From: PD on 12 Apr 2010 14:49
On Apr 11, 10:17 pm, Bill Bowden <wrongaddr...(a)att.net> wrote: > On Apr 11, 6:31 pm, "Androcles" <Headmas...(a)Hogwarts.physics_x> wrote: > > > > > "Bill Bowden" <wrongaddr...(a)att.net> wrote in message > > >news:2149aac2-5ed6-4f61-add9-13df873c2bb8(a)w17g2000yqj.googlegroups.com.... > > > > If fusion is a process of putting atoms together, and fission is a > > > process of breaking them apart, and both cases produce energy, then it > > > seems somewhat like a perpetual motion machine putting things together > > > and taking them apart while always producing energy. Where does the > > > extra energy come from? > > > > What am I missing? > > > > -Bill > > > That's a very good question, Bill. The thing to notice is that fission > > and fusion take place at opposite ends of the periodic table, with > > uranium (atomic weight 238, atomic number 92) splitting into smaller > > atoms, and hydrogen (atomic weight 1.0079, atomic number 1) > > combining with itself to form the heavier atom of helium (atomic > > weight 4.0026, atomic number 2). > > 4 * 1.0079 (H) = 4.0316, so 4.0316(He) -4.0026 = 0.029 units of atomic > > mass have radiated, so the sun shines. > > Atomic weight is the mass, atomic number is the charge, so the charge > > of 4 protons (H) has lost 2 (He) and two electrons are missing, two > > neutrons have appeared. > > In the middle of the table is iron, cobalt, nickel and copper from which > > you will not get much energy by either fission or fusion, it has reached > > the bottom. > > What we do not know is the precise method by which hydrogen ( of > > which there is plenty) can combine all the way up to the heavier elements, > > but it is theorised that this takes place in stars which implode/explode as > > supernovae and compress the lighter elements into the heavy in a final > > cataclysmic bang, so small chunks like the Earth (with a molten iron > > core) break off and the heavier elements that go with it have picked up > > some energy in the final cataclysm. > > We can never know for certain what goes on inside stars, we can only > > theorise. > > Thanks, that clarifies a bit. I guess the idea is on the way up from > the bottom, energy is obtained from electrons changing into neutrons > and some mass disappearing. Not sure how electrons change into > neutrons, or why the difference of potential. I get the general idea > of the strong nuclear force acting like a locked spring, so energy is > released when the lock breaks, but that's about it. Electrons are not turned into neutrons, and I don't know where you got the idea they are. In beta decay, a neutron transforms into a (lighter) proton and emits a W boson, which then commonly decays into an electron and an antineutrino. > > So, on the way down, energy is obtained when the strong nuclear force > loses hold (like a compressed spring with a open lock) and the atom > breaks apart into smaller atoms of less mass? > > And nobody knows how we get from ground zero past the iron/nickel > center barrier on the way up, other than it probably happens in > exploding stars? It is precisely in exploding stars where heavy elements are created, yes. > > Still sounds like witchcraft to me. > > -Bill |