Two spheres, P and Q, which are of equal radii, are placed on a smooth, horizontal surface. Their masses are in and 2m, respectively. Initially, sphere Q is at rest and sphere P is projected with speed u towards Q. When the spheres collide, the direction of P is 30° to the line through the centres of P and Q. Given that the coefficient of restitution between the spheres is 4/5, find the loss in kinetic energy due to the collision.