Why does the strong nuclear force become repulsive at small distances?

In summary, the strong nuclear force becomes repulsive at small distances because it requires a lot of energy to collapse the nucleus.
  • #1
Hootenanny
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This isn't a traditional homework question but here goes. I asked my physics tutor (A-Level) how the strong nuclear force becomes repulsive at small distances and he said he didn't know. I know that it is a nessecity that it is repulsive to prevent the nucleus collapsing, but I would like to know howit happens, are there any law's or mathematical derivations to prove this?

Any help / explanations would be great!
 
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  • #2
Hootenanny said:
This isn't a traditional homework question but here goes. I asked my physics tutor (A-Level) how the strong nuclear force becomes repulsive at small distances and he said he didn't know. I know that it is a nessecity that it is repulsive to prevent the nucleus collapsing, but I would like to know howit happens, are there any law's or mathematical derivations to prove this?

Any help / explanations would be great!
I'll take a stab at it. But you really should be talking to ZapperZ.

I would also suggest this be moved to the High energy, Nuclear, Particle physics section.

What makes you think that the strong force becomes repulsive at small distances? The reason the nucleus does not collapse is similar to the reason an atom does not collapse (negative electrons do not fall into the positive nucleus). It has to do with quantum mechanics. It does not require the concept of a force to keep the quarks apart or the electrons and protons apart.

If the electron fell into the nucleus, we would know its position to within a very small [itex]\Delta x[/itex]. So, the Heisenberg uncertainty principle says that its momentum range would be enormous. But this would require a huge amount of energy. Hence the probability that the electron will fall to the nucleus on its own is practically 0. Similarly, the energy required to collapse the three quarks in a nucleon is really enormous so the probability of nucleon collapse on its own is virtually 0.

But as I say, talk to ZapperZ.

AM
 
  • #3
Thank's the reason I think that it becomes negative is because of the graphs shown in my textbook, something similar to this;
http://webs.mn.catholic.edu.au/physics/emery/assets/9_5_op21.gif
I understand what you mean about the uncertainty principle though, has it got something to do with zero point motion?
 
  • #4
It is generally believed that the N-N potential has a hard repulsive core.
There have been attempts to get this with vector meson exchanges, but it is more easily seen as the Pauli principle for the quarks.
You can't put six quarks that close together.
The hard core has little to do with nuclear stability.
That is no different than hydrogen atom stability.
They both come from the lowest quantum state having a finite size.
 

FAQ: Why does the strong nuclear force become repulsive at small distances?

What is the Strong Nuclear Force?

The Strong Nuclear Force is one of the four fundamental forces of nature, along with gravity, electromagnetism, and the weak nuclear force. It is responsible for holding together the nucleus of an atom, which is made up of positively charged protons and neutral neutrons.

How does the Strong Nuclear Force work?

The Strong Nuclear Force works by exchanging particles called gluons between quarks, the subatomic particles that make up protons and neutrons. This force is very strong, but it only acts over extremely short distances, within the nucleus of an atom.

What is the range of the Strong Nuclear Force?

The range of the Strong Nuclear Force is very small, only about 10^-15 meters. This is because the force decreases rapidly as distance increases, making it only effective within the nucleus of an atom.

Why is the Strong Nuclear Force important?

The Strong Nuclear Force is important because it allows the nucleus of an atom to stay together despite the repulsive forces between positively charged protons. Without this force, atoms would not be able to exist and the universe would look very different.

Can the Strong Nuclear Force be broken?

The Strong Nuclear Force is the strongest of the four fundamental forces and cannot be broken or destroyed. However, it can be overcome under extreme conditions such as in nuclear reactions or in the center of a very dense object like a neutron star.

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