Strong nuclear forces act over incredibly short distances within atoms. They are effective at distances of about 1 femtometer (1 fm), which is one quadrillionth of a meter (10^-15 meters).

To put that into perspective:

* The diameter of a hydrogen atom is about 100,000 fm.

* The diameter of an atomic nucleus is about 10 fm.

This means that the strong nuclear force is only significant within the nucleus of an atom, holding the protons and neutrons together. Outside of this range, its influence rapidly decreases to zero.