Question

A river of width 500 m has flow velocity 3 m/s. A man starts swimming perpendicular to river flow at a speed of 4 m/s relative to water. Simultaneously a car starts moving on a road, that runs along the opposite side of the river, with constant speed. The car starts from a point on the other side that is exactly opposite to the point from where the man starts swimming. The speed of the car if both, the car and the man, meet at the same point at the moment man has crossed the river, is :

• A. 5 m/s
• B. 4 m/s
• C. 3 m/s
• D. √7 m/s.

Answer 1

Answer: (C)

3 m/s

Answer 2

$\overrightarrow{V}$_m,g = $\overrightarrow{V}$_m,r + $\overrightarrow{V}$_r,g

As both man and the car cover same distance along the flow in same time, their velocities along the flow must be same Man swimming in the river has velocity 3m/s acquired by the river in the direction of flow. Hence the car must also run by 3m/s.