Question

A man can row a boat with 4Km/h in still water, if he is crossing a river where the current is 2Km/h. [a] In what direction will his boat be headed if he wants to reach a point on the other bank, directly opposite to starting point? [b] If the width of the river is 500m, how long will it take to reach at that opposite point?

Answer 1

Answer:

For the boat to cross the river in the shortest time, the man should head the boat in the direction perpendicular to the river current.

Given : Velocity of man wrt river, V

MW

=4 km/hr

Velocity of river, V

R

=2 km/hr

d=4 km

Minimum time taken to cross the river

t=

V

MW

d

=

4

4

=1 hr