1. The problem statement, all variables and given/known data "A bar line AB has a length of 1,5m and a mass of 0,5kg. It is stuck in the point B in a horizontal fixed hub, and it can oscillate freely with no friction in the verical plane. at time t=0, the bar line, which was still (not moving, inertia), is set free to rotate. When it reaches the vertical position it hits a body of mass m2 = 0,2kg. The bar line immediately stops, while the body m2 begins to move after the collision with a horizontal velocity. Find: The angular velocity of the bar line, the linear velocity of its free extreme point (so A, i guess), and the velocity of m2 after the collision. 2. Relevant equations We have then: AB = 1,5m m1 = 0,5kg m2 = 0,2kg v0 = 0m/s 3. The attempt at a solution Alright, I didn't do too much actually, I am just starting out with these kind of problems. I understand that as soon as the bar line is set free, it starts a circular motion, and the final velocity depends on the gravity acceleration ( I guess ). And that the impact will be at angle teta = pi/2. Now, I don't really know where to start from. I am thinking about finding the center of mass, is that the right path to begin with?