# Strength of nuclear force: how does the nucleons stay in place?

Dr. Physics teaches us about the nuclear force, why is it needed in the nucleus, how strong it is and at what distances will it work. Note: there is some heavy physics around there and your head might hurt. i don’t understand most of the calculations done in there, but what I DO understand is the process.

At the level of nucleons, protons and neutrons, the gravitational force is way weaker than the electric force. Thus, protons would repel each other and the nucleus would not form. For example, Fg <<< Fe, the gravitational force is 10^30 times weaker than the electrical force between two protons. Thus you need the nuclear force to keep them packed in the nucleus. The nuclear force shows up between the color quarks that are inside each proton. The protons and neutrons are formed from up and down quarks: - protons - 2 up quarks and 1 down - neutrons - 2 down quarks and 1 up The up quark has a charge of +2/3 and the down quark has a charge of -1/3. this is why you can see why the proton is positive and the neutron is negative. Each proton and neutron also has color quarks. Color is used as a label here, it does not have anything to do with the color as we perceive it. The color quarks are: red, green, blue. Red attracts green and blue, but repels red and so on. Inside a nucleus it is these color quarks that are attracted to each other that bring the protons together. The energy used in there? -2.225 MeV. This is the binding energy. It is written with minus because it attracts particles. Also, the distance at which the nuclear force works is 2.2 fermi or 2.2 femtometers. The video from above has a ton of functions to calculate from and it shows even a couple of neat graphs. I could say that the video is 101 of nuclear force strength. Cool, ain't it?