A uniform solid cylindrical drum of mass 1.5kg and radius 0.5m is free to rotate about a fixed, smooth, horizontal axis which coincides with the axis of the cylinder. The axis is at a height of 2m above a horizontal table, and a light string of AB of length 4m has one end attached to the heighest point of the cylinder. A block of mass 0.3kg is attached to end B of the string and rests on the table. The drum begins to rotate at a constant angular speed of 4 rad s-1 in a clockwise direction. Calculate the angular speed of the drum immediately after the block is jerked into motion. I have no idea how to approach this question! The answer is supposed to be 2.86 rad s-1. Any help is greatly appreciated.