9709 P41 - Jun 2010 - Q6
3903
Particles A and B, of masses 0.2 kg and 0.45 kg respectively, are connected by a light inextensible string of length 2.8 m. The string passes over a small smooth pulley at the edge of a rough horizontal surface, which is 2 m above the floor. Particle A is held in contact with the surface at a distance of 2.1 m from the pulley and particle B hangs freely (see diagram). The coefficient of friction between A and the surface is 0.3. Particle A is released and the system begins to move.
- Find the acceleration of the particles and show that the speed of B immediately before it hits the floor is 3.95 m s-1, correct to 3 significant figures.
- Given that B remains on the floor, find the speed with which A reaches the pulley.
