How does strong force attracts nucleons

How, then, do protons and neutrons hold each other together? This can be described as a "leakage" or "residue" of the colour force between the quarks of the proton and the quarks of the neutron that pulls the proton and the neutron together.

This residual colour force therefore manifests itself as the strong nuclear force that binds "nucleons" -- a collective term for protons and neutrons in the nucleus -- together. This concept might be better understood if we understand that -- by analogy -- atoms, being electrically neutral, should not be attracted to other atoms to form molecules.

However, due to the composition of the atom positive nucleus and outer negative electron cloud , atoms do come together and form molecules. In an analogous way, we can understand the strong nuclear force by understanding the composition of the nucleons first.

There are other ways to answer this question, and one of them is the concept of binding energy. One of the tendencies of nature is to achieve stability. And a way to go about doing it is by minimizing the energy of a system.

When protons and neutrons "combine" to form a nucleus, we notice that the mass of the nucleus is less than the sum of the masses of the constituent nucleons. This is known as the "mass defect". How do we explain that? Essentially, it means that mass and energy are different forms of the same stuff just like potential energy and kinetic energy are but different types of the same thing called energy. As is discussed on the work page, the stronger the force or the greater the distance , the more energy is transferred for an interaction.

The strong force stores an incredibly large amount of energy in nuclei compared to the electromagnetic force , which is what governs chemical reactions. The big challenge is that very careful engineering is required to access the energy stored from the strong force. A full treatment of the strong force requires many years of intensive study. To learn more about the strong force please see the hyperphysics article on the strong force. Additionally, there is a comprehensive although longer article on what holds nuclei together by Prof.

Matt Strassler. Now, back to the nucleus. One thing that helps reduce the repulsion between protons within a nucleus is the presence of any neutrons. Since they have no charge they don't add to the repulsion already present, and they help separate the protons from each other so they don't feel as strong a repulsive force from any other nearby protons.

Also, the neutrons are a source of more strong force for the nucleus since they participate in the meson exchange. These factors, coupled with the tight packing of protons in the nucleus so that they can exchange mesons creates enough strong force to overcome their mutual repulsion and force the nucleons to stay bound together. Phone: Credits : Image credit: JLab. Caption :. Credits :. Star drop snapshot Ultra-short-distance interactions between protons and neutrons are rare in most atomic nuclei.

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