(a) A particle is suspended from a spring balance, which is fixed to the ceiling of a lift. When the lift is ascending with constant acceleration f m s-2, the spring balance shows a reading of 1-8 kg. 4. When the lift is descending with a constant acceleration - m s-2, the spring balance 3 shows a reading of 1 kg. Show that the mass of the particle is 1-2 kg. (i) Find the value of f. (ii) (b) A light smooth moveable pulley is connected by a light inextensible string which passes over a light smooth fixed pulley to a particle of mass 7 kg. Two particles, of masses 3 kg and 2 kg, are attached to the ends of a light inextensible string which passes over the moveable pulley. The system is released from rest. (i) Show, on separate diagrams, the forces acting on the smooth fixed pulley and on each of the particles. 7 kg (ii) Find, in terms of g, the acceleration of each of the particles. 2 kg (iii) The particle of mass 3 kg is replaced by a particle of mass x kg. Find the value of x for which the particle will not move when the system is released. 3 kg