question_answer

A river is flowing from east to west at a speed of 5 m/min. A man on south bank of river, capable of swimming 10m/min in still water, wants to swim across the river in shortest time. He should swim                                       [BHU 1998]

A)                 Due north

B)                             Due north-east

C)                 Due north-east with double the speed of river

D)                 None of these

Correct Answer: A

Solution :

                                For shortest time, swimmer should swim along AB, so he will reach at point C due to the velocity of river.                 i.e. he should swim due north.