9709 P41 - Jun 2011 - Q7
3566
Loads A and B, of masses 1.2 kg and 2.0 kg respectively, are attached to the ends of a light inextensible string which passes over a fixed smooth pulley. A is held at rest and B hangs freely, with both straight parts of the string vertical. A is released and starts to move upwards. It does not reach the pulley in the subsequent motion.
- Find the acceleration of A and the tension in the string.
- Find, for the first 1.5 metres of A’s motion,
- A’s gain in potential energy,
- the work done on A by the tension in the string,
- A’s gain in kinetic energy.
- B hits the floor 1.6 seconds after A is released. B comes to rest without rebounding and the string becomes slack.
- Find the time from the instant the string becomes slack until it becomes taut again.
