A 33,000 kg dump truck carrying gravel is passing across an 88.0 m flyover span from north to south. The flyover span can be considered a uniform structure of mass 200,000 kg. The center of mass of the truck is moving at a constant speed of 65.0 km/h. Determine the magnitude of the vertical force F_s(t) acting on the south end of the span during the travel of the truck as a function of time. (Assume at t = 0, the center of mass of the truck is at the north end on which the force F_n(t) acts.)