A bar of mass m resting on a smooth horizontal plane starts moving due to the force `F=mg//3` of constant magnitude. In the process of its rectilinear motion the angle `alpha` between the direction of this force and the horizontal varies as `alpha=as`, where a is a constant, and s is the distance traversed by the bar from its initial position. Find the velocity of the bar as a function of the angle `alpha`.

Answer

`v=sqrt((2g//3a)sin alpha)`