UPSEE Solved Model Paper 7

Let u and v represent the velocity of the river and that of the man, respectively
From the following figure, we see that for the man to travel by the shortest route AC
(

→

R

)， velocity of the man must lie along AB .

Using the law of vector addition,

→

AB

+

→

BC

=

→

AC

Given:
u = 2 km/h
v = 5 km/h
The direction (6) in which the man should swim is given by
sin θ =

BC

AB

=

u

v

⇒ sin θ =

2‌km∕h

5‌km∕h

= 0.4
⇒ θ = sin−1(0.4)
Thus, the man should swim at an angle of "sin−1(0.4) West of North".
Hence, option 'C' is correct.