The strong force keeps also the protons together in the nucleus, despite their mutual electrostatic repulsion.
Contemporary Physics Education Project

The Nuclear Force

The protons in the nucleus of an atom are positively charged. If protons interact, they are usually pushed apart by the electromagnetic force. (Remember, opposite charges attract, but like charges repel!). However, when two or more nuclei come VERY close together, the nuclear force comes into play. The nuclear force is a hundred times stronger than the electromagnetic force so the nuclear force may be able to "glue" the nuclei together so fusion can happen.

The nuclear force is also known as the strong force. This is one of the four fundamental forces in the Universe.

The nuclear force keeps together the most basic of elementary particles, the quarks. Quarks combine together to form the protons and neutrons in the atomic nucleus.


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