Strong Nuclear Force
The short-range attractive force that binds protons and neutrons together within the nucleus.
Unit
N
In depth
Around a hundred times stronger than electrostatic repulsion, the strong force acts only over about 10⁻¹⁵ m — roughly the diameter of a nucleon. Because it is so short-ranged while repulsion is not, large nuclei need extra neutrons to stay bound and eventually become unstable.
Examples in the real world
It holds the 92 mutually repelling protons of a uranium nucleus together, though only just.