A small block (block 1) of mass m, attached to an ideal string of length L, is initially held so that the string is taut and horizontal at height L above a frictionless table, as shown in Fig.2. A second small block (block 2) of mass 3m is placed on the table right under the point of attachment of the string holding block 1. The tabletop is at height 2L above the floor. Block 1 is then released from rest point of attachment m block 1 block 2 3m and collides elastically with block 2 at time t=0. The acceleration due to gravity has magnitude g and air resistance is negligible. 2L Figure 2

A small block (block 1) of mass m, attached to an ideal string of length L, is initially held so that the string is taut and horizontal at height L above a frictionless table, as shown in Fig.2. A second small block (block 2) of mass 3m is placed on the table right under the point of attachment of the string holding block 1. The tabletop is at height 2L above the floor. Block 1 is then released from rest point of attachment m block 1 block 2 3m and collides elastically with block 2 at time t=0. The acceleration due to gravity has magnitude g and air resistance is negligible. 2L Figure 2