Gre Problem # 64 symmetric fission

In summary, the problem provided does not contain enough information to solve it accurately. However, basic knowledge of nuclear physics can help narrow down the options. The correct answer is most likely (C) 200 MeV, as heavy nuclei that undergo fission typically have a large number of nucleons. This highlights the need for additional knowledge and assumptions when answering GRE questions.
  • #1
quantumworld
36
0
Dear forum contributer,

The binding energy of a heavy nucleus is about 7 Mev per nucleon, whereas the binding energy of a medium-weight nucleus is about 8 Mev per nucleon. Therefore, the total kinetic energy liberated when a heavy nucleus undergoes symmetric fission is most nearly
(A) 1876 Mev
(B) 938 Mev
(C) 200 Mev
(D) 8 Mev
(E) 7 Mev

I found that this problem needs more info in order to be solved, I mean for example, if they said the heavy nucleus is Uranium of atomic weight 238, or something like that, I would have been able to calculate the energy liberated, by saying, the heavy nucleus will become medium nucleus by delivering 1 Mev per nucleon, so with 238 the energy liberated willl be around 200 Mev, which is the correct answer, but with only the given info, I would not be able to solve it :confused:

Many thanks
 
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  • #2
quantumworld said:
Dear forum contributer,

The binding energy of a heavy nucleus is about 7 Mev per nucleon, whereas the binding energy of a medium-weight nucleus is about 8 Mev per nucleon. Therefore, the total kinetic energy liberated when a heavy nucleus undergoes symmetric fission is most nearly
(A) 1876 Mev
(B) 938 Mev
(C) 200 Mev
(D) 8 Mev
(E) 7 Mev

I found that this problem needs more info in order to be solved, I mean for example, if they said the heavy nucleus is Uranium of atomic weight 238, or something like that, I would have been able to calculate the energy liberated, by saying, the heavy nucleus will become medium nucleus by delivering 1 Mev per nucleon, so with 238 the energy liberated willl be around 200 Mev, which is the correct answer, but with only the given info, I would not be able to solve it :confused:

Many thanks

Well, you are right, more is needed than what is given. This is often the case with GRE questions. But what is required is simply basic knowledge that anybody studying physics can be expected to have. This problem is a good example. Nuclei which undergo fission are heavy nuclei, typically above iron. So they won't have only a handful of nucleons, which rule out the 7 or 8 MeV answers. On the other hand, there is no nucleus with a thousand or more nucleons, so this rules out the large answers. The only number that makes any kind of sense is the 200 MeV.

So I agree that extra knowledge is necessary, but it's basic knowledge. You have to expect that kind of situation, where extra knowledge is assumed, in GRE questions.

Pat
 
  • #3
for your contribution to the forum and for bringing up this important point. The problem does indeed require more information in order to be solved accurately. As you mentioned, the type of heavy nucleus and its atomic weight would be necessary to calculate the energy liberated during symmetric fission. Without this information, it is impossible to determine the accurate answer. Therefore, the best course of action would be to request more information from the source of the problem or to move on to the next question. Thank you for bringing this up and reminding us to always consider all necessary information in problem-solving.
 

1. What is symmetric fission?

Symmetric fission is a type of nuclear reaction where the nucleus of an atom splits into two nearly equal fragments, releasing a large amount of energy.

2. How does symmetric fission occur?

Symmetric fission occurs when a heavy atom, such as uranium, absorbs a neutron and becomes unstable. The nucleus then splits into two smaller nuclei, releasing multiple neutrons and a significant amount of energy.

3. What is the significance of symmetric fission in nuclear energy production?

Symmetric fission is the basis for nuclear power plants, where the energy released from fission reactions is harnessed to generate electricity. It is also used in nuclear weapons, where the energy released is used for destructive purposes.

4. Can symmetric fission occur naturally?

No, symmetric fission does not occur naturally. It is a controlled process that requires specific conditions, such as a high concentration of enriched uranium, to occur.

5. What are the potential risks associated with symmetric fission?

The main risk associated with symmetric fission is the release of harmful radiation during the reaction. This can have detrimental effects on human health and the environment if not properly contained and managed. There is also a risk of accidents or malfunctions in nuclear power plants, which can result in the release of radioactive materials.

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