Why do fusion and fission both release energy

Here m is Mass of original element - Mass of new elements and c is the speed of light. I wanted to mention that is technically much more complicated than what I say here. The short answer is still the same: Mass is converted into Energy.

Wanted to provide a quick answer, but apparently now is frowned upon to give quick answers in comments, so here it is:. Roughly speaking, nuclear fission is endothermic for nuclei where nuclear fusion would be exothermic, and viceversa. For nuclei smaller than Iron, fission is typically endothermic, while fusion is exothermic.

For nuclei heavier than Iron, the situation reverses. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why do fusion and fission both release energy? Ask Question. Asked 2 years, 9 months ago. Active 2 years, 9 months ago. Viewed 21k times. Improve this question.

It can also happen when a single slow neutron merges with the nucleus. How does the entropy of the system change when fission or fusion occur and why does this depend on the size of the nucleus? Please keep in mind that comments are to be used for suggesting improvements and requesting clarification on their parent post i.

Add a comment. Active Oldest Votes. Purely classical model Nucleons are bound together with the strong and some weak nuclear force.

Equivalently, the binding energy per nucleon behaves similarly. This image from Wikipedia illustrates the curve in the typically presented manner: However, I prefer to think of binding energy as negative and therefore better visualize iron as being the lowest energy state: For lighter elements: Fission requires energy Fusion releases energy For heavier elements, the opposite is true.

The reason we mainly observe the release energy cases is because: It is easier to do It is more "useful". Improve this answer. Keith Keith 1, 9 9 silver badges 9 9 bronze badges.

What makes it "cold" is that supposedly you could somehow get it to happen without going through an intermediate stage that costs a lot of energy to get to -- namely where two nuclei are close enough together that you've spent a lot of energy overcoming their electrostatic repulsion but not yet so close together that the strong force has begun attracting them.

This energy cost is not lost; it will be paid back either when fusion happens, or if fusion fails to happen, then when the nuclei are forced apart again at high speed by electrostatic forces.

But getting that much energy concentrated in a pair of nuclei in the first place is the major technological problem in fusion power, and the only known way to achieve it in quantity is to heat up a plasma to insane temperatures. Cold fusion would -- in some way never quite explained -- mean a way to avoid this barrier.

Muons decay fairly rapidly so they cannot be stored, and they take a lot of energy to produce. Show 2 more comments. But the issue I was trying to shed some light on, which deserves it, is that in fission and fusion, the universe loses a tiny little bit of mass. This mass loss is what enables us to extract useful work.

However, if you try to fuse anything above iron, or fise.. Show 10 more comments. On a nucleus basis, fission triumphs again. Fusion far exceeds fission in power output. The only reason we use fission plants is that fusion is much, much harder to do. Splitting one uranium nucleus releases more energy than fusing two lighter nuclei of any kind.

Show 1 more comment. Thomas Fritsch Thomas Fritsch 21k 9 9 gold badges 49 49 silver badges 75 75 bronze badges. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The leftover mass becomes energy. If scientists develop a way to harness energy from fusion in machines on Earth, it could be an important method of energy production.

Fusion can involve many different elements in the periodic table. However, researchers working on fusion energy applications are especially interested in the deuterium-tritium DT fusion reaction. That is why very large nuclei transuraniums are unstable. For nuclei bigger than iron the overall energy loss due to mutual repulsion is more important than the energy gain due to smaller surface. More about the liquid drop model.

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