Two blocks of mass `m_(1) and m_(2)` are connected to the ends of a spring. The spring is held compressed and the system is placed on a smooth horizontal table. The block of mass `m_(1) = 2 kg` is kept at `x = 1 cm` mark and the other block is at `x = 2 cm` mark. The system is released from this position. It was observed that at the instant `m_(1)` was at `x = 5 cm` mark its velocity was zero and at that moment `m_(2)` was located at `x = -4 cm`. Find mass `m_(2)` and unstretched length `(l_(0))` of the spring