A horizontal rod of length l=2 m and mass 2 kg with the balls A and B of mass 1 kg each at its ends is clamped at the centre C in such a way that it can rotate freely about a horizontal axis through the clamp. The system is kept at rest in the horizontal position. A particle P of mass 1 kg is dropped from a height of 5 m on the ball B. The particle collides with B and sticks to it. Find the angular velocity of the system just after the collision.