Two balls, X and Y, move along a horizontal frictionless surface, as illustrated in Fig. 3.1. Ball X has an initial velocity of 3.0ms⁻¹ in a direction along line AB. Ball Y has a mass of 2.5kg and an initial velocity of 9.6ms⁻¹ in a direction at an angle of 60° to line AB. The two balls collide at point B. The balls stick together and then travel along the horizontal surface in a direction at right-angles to the line AB, as shown in Fig. 3.2.