The diagram shows a velocity-time graph which models the motion of a tractor. The graph consists of four straight line segments. The tractor passes a point O at time \(t = 0\) with speed \(U \text{ m s}^{-1}\). The tractor accelerates to a speed of \(V \text{ m s}^{-1}\) over a period of 5 s, and then travels at this speed for a further 25 s. The tractor then accelerates to a speed of 12 \(\text{ m s}^{-1}\) over a period of 5 s. The tractor then decelerates to rest over a period of 15 s.

1. Given that the acceleration of the tractor between \(t = 30\) and \(t = 35\) is \(0.8 \text{ m s}^{-2}\), find the value of \(V\).
2. Given also that the total distance covered by the tractor in the 50 seconds of motion is 375 m, find the value of \(U\).