River width L = 300m, river velocity V1 = 3m / s, ship velocity V2 = 5m / s in still water If crossing the river with the shortest displacement, what is the sailing time and angle of the ship In addition, if the ship's speed is vertical, what is the combined speed of the ship's speed and water speed? Is V1 vertical to V2? What is the angle

River width L = 300m, river velocity V1 = 3m / s, ship velocity V2 = 5m / s in still water If crossing the river with the shortest displacement, what is the sailing time and angle of the ship In addition, if the ship's speed is vertical, what is the combined speed of the ship's speed and water speed? Is V1 vertical to V2? What is the angle

If crossing the river with the shortest displacement, the combined velocity is: v = (V2 ^ 2-v1 ^ 2) ^ 1 / 2 = (5 ^ 2-3 ^ 2) ^ 1 / 2 = 4m / s, so the time is: T = s / v = 300m / (4m / s) = 75s, the angle between the bow direction and the river bank is set as θ: cos θ = V1 / V2 = 3 / 5, so θ = 53 ° if the bow is vertical to the river bank, the combined velocity is: v = (V1 ^ 2 + V2 ^ 2) ^ 1 /