Question

A river is flowing from west to east at a speed of $5m/min$. A man on the south bank of the river, capable of swimming at $10m/min$ in still water, wants to swim across the river in the shortest time. Finally he will move in a direction.

• A. ${\tan }^{-1}\left(2\right)E$ of $N$
• B. $ta{n}^{-2}\left(2\right)N$ of $E$
• C. ${30}^{\circ }E$ of $N$
• D. ${60}^{\circ }E$ of $N$

Answer 1

The correct option is B $ta{n}^{-2}\left(2\right)N$ of $E$

Finally, he will swim along $B.\tan \theta =\frac{v}{u}=\frac{10}{5}=2$
$\Rightarrow \theta ={\tan }^{-1}\left(2\right)N$ of $E$.