A river is flowing due east with a speed `3ms^(-1)`. A swimmer can swim in still water at a speed of `4ms^(-1)`. If swimmer starts swimming due north, then the resultant velocity of the swimmer is

Options

A. `3ms^(-1)`
B. `5ms^(-1)`
C. `7ms^(-1)`
D. `2ms^(-1)`

Answer

B

Explanation

Here, Velocity of water flowing in river, `n_(r)=3ms^(-1)`
Velocity of swimmer in still water, `n_(s)=4ms^(-1)`
From fig. The resultant velocity of the swimmer is
`V=sqrt(V_(s)^(2)+V_(r)^(2))=sqrt((4)^(2)+(3)^(2))=sqrt(25)=5 ms^(-1)`