2025 NASS PRELIMS P1 Q13

In the diagram, a surveillance camera is mounted at point \(P\), 20 m vertically above point \(Q\). A runner runs from point \(Q\) along a straight road at a speed of 4 m/s. The surveillance camera tracks the motion of the runner by panning upwards and downwards at point \(P\). Find the rate of change of the angle that the surveillance camera makes with \(PQ\) when the runner is 15 m from \(Q\). Give your answer in radians per second.[5]