申論題

4.(20%) The boat has a mass of I 80 kg and is traveling forward on a river with a constant velocity of 70 kn/h. measured relative to the river. The river is flowing in the opposite direction at 5 km/h. If a tube is placed in the water, as shown, and it collects 40 kg of water in the boat in 80 s, determine the horizontal thrust T on the tube that is required to overcome the resistance due to the water collection and yet maintain the constant speed of the boat. ( Pw = 1 Mg/m³)