A particle, P, is placed on a large, rough, horizontal disc. P is of mass 2.4 kg. The particle is then attached to a light, inextensible string of length 4 m. The string passes through a smooth hole in the centre of the disc, and at the other end is a particle, Q, of mass 3 kg. The coefficient of friction between P and the disc is 0.2. Q is hanging freely under the hole in the disc. The disc is set spinning with P at a distance of 1.2m from the centre of the disc. If Q does not move at any point during the motion, find the range of speeds possible.