3 Two particles \(A\) and \(B\), of masses 2.4 kg and 1.2 kg respectively, are connected by a light inextensible string which passes over a fixed smooth pulley. \(A\) is held at a distance of 2.1 m above a horizontal plane and \(B\) is 1.5 m above the plane. The particles hang vertically and are released from rest. In the subsequent motion \(A\) reaches the plane and does not rebound and \(B\) does not reach the pulley.

1. Show that the tension in the string before \(A\) reaches the plane is 16 N and find the magnitude of the acceleration of the particles before \(A\) reaches the plane.
2. Find the greatest height of \(B\) above the plane.