Homework Help: M1 Mechanics Help.

1. Feb 8, 2004

Darren

Hi all, i have been really stuck with this question for hours now,

Two particles "P" and "Q" of masses 1Kg and 2Kg respectively are hanging vertically from the ends of a light inextensible string which passes over a smooth fixed pulley. The system is released from rest with both particles a distance of 1.5m above a floor. When the masses have been moving for 0.5s the string breaks.

Find the futher time that elapses before "P" hits the floor.

This has just got me totally confused, and to be honest i have no idea how to start, i have the picture drawn but am looking at it blankly. Any help is much appreciated.

Daz.

2. Feb 8, 2004

Norman

So you will need to find the distance P moves in 0.5s and its velocity at that point. Then when the string breaks, your velocity at the point becomes your initial velocity at a height 1.5 + D, where
D is the distance that P moved in the first part. P is now only subjected to the acceleration due to gravity and it is a simple kinematics problem.
Good luck,
Norm