Particle \(P\) has mass \(3 m\) and particle \(Q\) has mass \(m\). The particles are moving towards each other in opposite directions along the same straight line on a smooth horizontal plane. The particles collide directly. Immediately before the collision the speed of \(P\) is \(u\) and the speed of \(Q\) is \(3 u\). In the collision, the magnitude of the impulse exerted by \(Q\) on \(P\) is \(5 m u\).
Find the speed of \(P\) immediately after the collision.
Find the speed of \(Q\) immediately after the collision.