A massless inextensible string runs over a massless frictionless pulley. One end is attached to a block of mass
m that hangs vertically. The other end is fixed to a wall so that the segment between the pulley and the wall is horizontal and has length
L. A second mass
m is attached to the string at the midpoint of this horizontal segment and held there, keeping the string taut and straight. The second mass is then released from rest. Neglect any losses. What is the
maximum height the block rises above its initial position during the subsequent motion?