# A man can swim at 3 km/hr in a static river. If he wants to cross a river of width 500 m in shortest possible time, then at what angle with repect to direction of motion he should move? Option 1) $0\degree$ Option 2) $45 \degree$ Option 3) $60\degree$ Option 4) $90\degree$

P Prateek Shrivastava

As we have learnt

Boat - River Problem -

To cross the river in the shortest time.

- wherein

Drift along river flow $x= d\left ( \frac{u}{v} \right )$

If he wants to cross the river in shortest possible time, then he must move along a direction per pendicular to direction of river flow.

Option 1)

$0\degree$

Option 2)

$45 \degree$

Option 3)

$60\degree$

Option 4)

$90\degree$

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