Question 193 of 308

The stream of a river is flowing with a speed of $2km{h}^{-1}$. A swimmer can swim at a speed of $4km{h}^{-1}$. The direction of the swimmer with respect to the flow of the river, to cross the river straight, is

A$150^{\circ}$B$90^{\circ}$C$120^{\circ}$D$60^{\circ}$

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Answer: (C) $120^{\circ}$

To reach the point directly opposite to the starting point, the resultant velocity of swimmer should be as shown in figure.



From figure
$\sin ⁡\theta =\dfrac{2}{4}=\dfrac{1}{2}$
$\theta =30^{\circ}$
Angle with flow $=90^{\circ}+30^{\circ}=120^{\circ}$