(a)[2]
State what a photon is.
(b)
A stationary cobalt-60 ($^{60}_{27}\text{Co}$) nucleus emits a $\gamma$-ray photon with an energy of $1.18\,\text{MeV}$.
(b(i))[2]
Calculate the wavelength of this photon.
(b(ii))[2]
Show that the photon momentum is $6.3 \times 10^{-22}\,\text{N s}$.
(c)[2]
Use information in (b)(ii) to find the recoil speed of the cobalt-60 nucleus when the $\gamma$-ray photon is emitted.