In Section 13 4,  we have seen that for average mass
nuclei the binding energy per nucleon is  approximately 8 MeV, which is
much larger than the binding energy in atoms Therefore, to bind a
nucleus together there must be a strong attractive force of a totally
different kind It must be strong enough to overcome the repulsion
between the (positively charged) protons and to bind both protons and
neutrons into the tiny nuclear volume