A river is flowing from west to east at a speed of 5 metres per minute. A man on the south bank of t

Question

A river is flowing from west to east at a speed of 5 metres per minute. A man on the south bank of the river, capable to swimming at 10 metres per minute in still water wants to swim across the river in the shortest time. He should swim in a direction\

Professor PC Thomas Classes · Answer

River flowing with a velocity $u$ and the person wanting to cross the river in the shortest time.\ He will have two velocities $u$ and $v$ at right angles. His resultant velocity will be $\sqrt{\mathrm{v}^{2}+\mathrm{u}^{2}}$ along AC. So he will reach the point $C$ instead of $B$. Time taken $t_{2}=\frac{d}{v}$ itself. The distance BC across which he is carried down stream $=\mathrm{BC}=\mathrm{ut}_{2}$.\