Forces and equilibrium — practice question

A ring $P$ of mass $0.03\,\text{kg}$ is fitted on a rough vertical rod. A light inextensible string is fastened to the ring and pulled upwards at an angle of $15^\circ$ to the horizontal. The tension in the string is $2.5\,\text{N}$ (see diagram). The ring is in limiting equilibrium and is just about to slide up the rod.