Two small smooth spheres A and B, of equal radii and of masses \(km\) kg and \(m\) kg respectively, where \(k > 1\), are free to move on a smooth horizontal plane. A is moving towards B with speed 6 m s^-1 and B is moving towards A with speed 2 m s^-1. After the collision A and B coalesce and move with speed 4 m s^-1.

1. Find \(k\).
2. Find, in terms of \(m\), the loss of kinetic energy due to the collision.