# Nucleon Bound Energies

1. Jan 11, 2014

### evamaster

I was reading my quantum mechanics text and I have a doubt. I have the energy levels well defined for the finite square well and the author suddenly compares (I believe) those levels with the levels of the nucleon with the following phrase: "is the spacing between levels on the order of MeV for a nucleon bound in a several-fm well?". So I have some troubles understanding the meaning of that particular pharse.

Thanks.

2. Jan 11, 2014

### edguy99

Sometimes a visual can help, the scale along the bottom is in femto-meters (fm), the distance where the strong force is "very" strong.

3. Jan 11, 2014

### evamaster

Ok thanks but what does it mean the pink and blue graphs?
And what does it mean a very strong force?

4. Jan 11, 2014

### Jilang

It looks like the blue line represents the well and the pink line might be an energy level at 8Mev. The strong force is responsible for holding the nucleons together, but it only acts over a small distance. From the graph it looks like that distance is about 10 fm.

5. Jan 11, 2014

### edguy99

Unlike gravity where the force you feel from the earth drops off slowly as you move away from earth according to what is called the the inverse square law, the strong force (that holds neutrons and protons together) is very different. With the strong force, if you are within a few femto-meters of the other guy you feel a very large attraction. If you get out a little, say 20 femtometers away, you don't feel an attraction at all to the other neutrons and protons.