A load is suspended from the free end of the thread attached to the wall and thrown over the roller. The roller is fixed on a bar of mass m₀, which can slide along a horizontal plane without friction. At the initial moment, the thread with the load is deflected from the vertical by an angle α and then released. Determine the acceleration of the bar if the angle formed by the thread with the vertical does not change during the movement of the system. What is the weight of the cargo?