Task id16151

On a weightless rod of length I the following are attached: a) a mass 2m at the end of the rod, b) two equal masses m - one at the end of the rod, the other in the middle of the rod (Fig.). The rod can rotate in a vertical plane around point A. In both cases, what horizontal speed must be imparted to the end of the rod in order for it to deflect to a horizontal position?