The ship moves perpendicular to the coast at a speed of 7.2 km / h. Find the movement of the ship

The ship moves perpendicular to the coast at a speed of 7.2 km / h. Find the movement of the ship relative to the coast if the ship reached the second coast after 200 seconds. During this time, the current carried the ship 300 m down the river. I solve using the Pythagorean formula S = root of S1 + S2. S2 = 300 m as required. And S1 = V * t. So that’s what bі everything coincided, it is necessary that V1 = 2. Why, if the condition has a different meaning.

Vк = 7.2 km / h = 2 m / s.

t = 200 s.

S1 = 300 m.

S -?

The movement of the ship S is a vector that connects its initial and final positions.

Since the ship moves along the river, the water of which has a current velocity Vt, it is carried along the current at a distance S1, which

The movement of the ship S relative to the starting point of movement will be the hypotenuse of a right-angled triangle, the legs of which will be the width of the river S2 and the movement of the ship along the coast of S1.

By the Pythagorean theorem: S = √ (S1 ^ 2 + S2 ^ 2).

Since the ship was moving uniformly perpendicular to the bank at a speed Vк, then the width of the river is expressed by the formula: S2 = Vк * t.

S = √ (S1 ^ 2 + (Vk * t) ^ 2).

S = √ ((300 m) ^ 2 + (2 m / s * 200 s) ^ 2) = 500 m.

Answer: the movement of the ship was S = 500 m.