Why is energy released during nuclear fission?

In summary, when a massive nucleus, such as Uranium, splits into smaller fragments, the resulting fragments have a higher binding energy per nucleon. This means that the total energy released from the fission reaction will be positive, as the mass-energy of the fragments is lower than the original nucleus. This is due to the fact that the binding energy per nucleon is greater in the smaller fragments, leading to a release of energy.
  • #1
Boomka
1
0
When a massive nucleus splits, it forms two smaller fragments. For Uranium, we have A=235, and the typical fragments are A=140 and A=95. Looking at the binding energy curve, these two fragments have greater binding energy per nucleon than the original uranium nucleus. Hence, if the uranium nucleus splits in this way, energy will be released.

I think i do understand why the binding energy is higher for the fragments, however I don't understand why energy is released.

Could someone please explain in simple language.

Thank you
 

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  • #2
Binding energy is not what determines the available energy.
The available energy/c^2 equals the nuclear mass of Uranium minus the masses of the two fragments and the neutrons released.
 
  • #3
Boomka, the mass-energy of a nucleus is approximately A (Mc2 - B) where A is the atomic weight, M is the mass of a nucleon and B is the binding energy per nucleon. When a nucleus fissions, the total mass-energy of the two daughter nuclei will be A1 (Mc2 - B1) + A2 (Mc2 - B2). Ignoring the few neutrons that escape ("fast neutrons"), A = A1 + A2. We still have the same number of nucleons, so the Mc2's on both sides cancel. And since B1 ≈ B2, we find that the energy released will be A (B1 - B). As you point out, B1 > B, so the energy released is positive.
 

1. What is fission and how does it relate to E=mc^2?

Fission is a nuclear reaction in which a large nucleus is split into smaller nuclei, releasing a large amount of energy. E=mc^2, also known as Einstein's famous equation, explains the relationship between mass and energy. In fission, the mass of the original nucleus is converted into energy according to this equation.

2. How was fission discovered?

Fission was discovered by German physicists Otto Hahn, Lise Meitner, and Fritz Strassmann in 1938. They conducted experiments using uranium and noticed that it was splitting into smaller nuclei and releasing energy.

3. Can fission be controlled?

Yes, fission can be controlled through the use of a nuclear reactor. In a nuclear reactor, the fission process is carefully controlled to generate heat, which is then used to produce electricity.

4. What are the potential risks and benefits of fission?

The potential risks of fission include the possibility of a nuclear meltdown or radiation leaks, which can have serious consequences for human health and the environment. However, fission also has the potential to provide a large amount of energy and is a relatively clean source of energy compared to fossil fuels.

5. What is the role of E=mc^2 in nuclear weapons?

E=mc^2 plays a crucial role in the development and functioning of nuclear weapons. The equation explains how a small amount of mass can be converted into a large amount of energy. In nuclear weapons, this energy is released through the process of fission or fusion, resulting in a powerful explosion.

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