Question

A swimmer starts to swim from point a to cross a river. He wants to reach point B on the opposite side of the river. The line AB makes an angle `60^(@)` with the river flow as hown. The velocity of the swimmer in still water is same as that of the water

(i) In what direction should he try to direct his velocity ? Calculate angle between his velocity anf river velocity.
(ii) Find the ratio of the time taken to cross the river in this situation to the minimum time in which he can cross this river.

Answer 1

Correct Answer - (a) `120^(@)` (b) `2//sqrt(3)`
From figure (a) `120^(@)`
time to cross ` = (2d)/(sqrt(3) V)`
Minimum time `t = (d)/(v)`
`:.` Ratio `= 2 sqrt(3)`.