4 A particle \(P\), of mass 6 kg , is attached to one end of a light inextensible string. The string passes through a small smooth ring, fixed at a point \(O\). A second particle \(Q\), of mass 8 kg , is attached to the other end of the string. The particle \(Q\) hangs at rest vertically below the ring, and the particle \(P\) moves with speed \(5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) in a horizontal circle, as shown in the diagram. The angle between \(O P\) and the vertical is \(\theta\).
\includegraphics[max width=\textwidth, alt={}, center]{7c2c50e0-4976-4301-9898-61b2760a2aee-10_517_433_683_790}

1. Find the tension in the string.
2. \(\quad\) Find \(\theta\).
3. Find the radius of the horizontal circle.
   [0pt] [4 marks]