A tugboat pulls a small barge through a harbor. The propeller thrust minus the drag produces a net thrust that varies linearly with speed. Knowing that the combined weight of the tug and barge is 3600 kN, determine; (a) the time required to increase the speed from an initial value v1 = 1.0 m/s to a final value v2 = 2.5 m/s and (b) the distance traveled during this time interval.