Gravity does not play any role in the strength of the strong force within protons. The strong force is one of the four fundamental forces in nature and is responsible for binding the quarks together inside protons and neutrons. It is much stronger than gravity but has a very short range, acting over distances of about 1 femtometre (10^-15 metres).

The strong force is mediated by the exchange of particles called gluons, and its strength is determined by the colour charge of the quarks. Protons and neutrons are composed of three quarks each, and the colour charges of these quarks combine to give the proton a net colour charge of zero. This means that the strong force between the quarks in a proton is balanced, and the proton is stable.