AQA A-Level Physics/Particles and Anti-particles/Forces
You may have learnt that there are many different types of forces such as friction and tension. However only four fundamental forces are at a basic level responsible for all interactions in the universe.
Strong Nuclear Force
This type of force is only experienced by baryons (hadrons with 3 quarks). The exchange particles for this force are gluons. This force is responsible for keeping the protons and neutrons in a atomic nucleus together. The strong nuclear force only acts over a short range of 3fm. Between the distance of 3fm and 0.5fm separation the strong nuclear force is attractive. Below 0.5fm separation the strong nuclear force is repulsive.
Weak Nuclear Force
This type of force is experienced by both baryons and leptons. The exchange particle for this type of force is the W or the K boson. This force is responsible for decay interactions (such as beta decay) and interactions where strangeness is not conserved or where quarks change flavour (or type).
This type of force is experienced by particles which are charged (such as electrons and protons). The exchange particle for this type of force is the virtual photon. This force is responsible for the repulsion of two electrons and attraction of a electron to a proton.