Quick questions on The four fundamental forces (QCE Physics Unit 4)

Gluon (8 types). Massless. Carry colour charge.

Quarks (and hadrons by extension).

$\sim 1$ (the reference strength; about 100 times stronger than electromagnetism at this distance).

About $10^{-15}$ m (one femtometre, nuclear size). Effectively confining for quarks; never observed in isolation.

Binds quarks into hadrons. The residual strong force (sometimes called the nuclear force) binds protons and neutrons into nuclei despite Coulomb repulsion between protons.

Without it, no atomic nuclei beyond hydrogen would be stable (Coulomb repulsion would tear them apart). No stars, no elements heavier than hydrogen, no life.

Without it, no atoms (electrons would not bind to nuclei). No chemistry, no light, no electromagnetism. Most of everyday physics.

Without it, no beta decay; the cosmic distribution of elements would be very different. The hydrogen fusion in the sun begins with a weak-force process (proton-proton fusion via a W boson), so without the weak force, the sun would not shine. Most natural radioactive decays involve the weak force.

Without it, no large-scale structure (stars, planets, galaxies). Negligible at scales below planets, but cumulatively decisive at astronomical scales.

List the four fundamental forces in order of decreasing relative strength. [2 marks]

Identify the gauge bosons that mediate the strong and electromagnetic forces, and state the range of each. [3 marks]

A cobalt-$60$ source undergoes beta-minus decay. (a) Identify the fundamental force responsible and the mediating boson. (b) Justify why this force is weaker than electromagnetism.