Use \(g=10\text{ m s}^{-2}\), except where an answer in terms of \(g\) is requested.

Particles \(A,B\), of masses \(km,m\) respectively, move in a straight line on a smooth horizontal plane. \(A\) is projected towards \(B\) at speed \(2u\), simultaneously \(B\) is projected towards \(A\) at speed \(u\). After collision \(A\) has speed \(u\), and both move in the direction of \(A\)’s original motion. Exactly 35% of total kinetic energy is lost. Find the speed of \(B\) after collision in terms of \(u\). [8]