A ball is attached to one end of a wire, the other end being fastened to the ceiling. The wire is held horizontal and the ball is released from rest. It swings downward and strikes a block initially at rest on a horizontal frictionless surface. Air resistance is negligible, and the collision is elastic. The mass of the ball is 1.6kg and the mass of the block is 2.4kg and the length of the wire is 1.2m. Find the velocity just before and just after the collision.