Hand written solution required

Two particles A and B of masses 4 kg and 2 kg respectively are connected by a light inextensible string. The particles are at rest on a smooth horizontal plane with the string slack. Particle A is projected directly away from B with speed ums-!. When the string goes taut the impulse transmitted through the string has magnitude 6 Ns. Find: a the common speed of the particles just after the string goes taut (4 marks) b the value of u