Question

A river is flowing from west to east at a speed of $5m/mi{n}^{-1}$. A man on the south bank of the river, capable of swimming at $10m/mi{n}^{-1}$in still waters wants to swim the river in the shortest time. In which direction should swim in a direction

• A. ${30}^{\circ }$ west of north
• B. ${60}^{\circ }$ east of north
• C. ${30}^{\circ }$ east of north
• D. due north

Answer 1

Answer: (D)

due north

To reach the opposite bank of the river in minimum time, the swimmer should swim at right angles to the direction of flow of river. He should swim in a direction due north.