Targ S.M. 1988 D1 option 51

A load D of mass m, having obtained at point A an initial velocity V₀, moves in a curved pipe ABC. In section AB, in addition to gravity, a constant force Q and a resistance force R of the medium act on the load. At point B, the load, without changing its speed, goes to the pipe section BC, where, in addition to gravity, the variable force F acts on it. Find the law of cargo movement on section BC. Neglect the friction of the load on the pipe. Given: m = 2kg; V₀=20m / s; Q = 6H; R = 0.4v; t₁ = 2.5c; Fx = -5cos (4t).