Question

A person aiming to reach exactly opposite point on the bank of a stream is swimming with a speed of $0.5 \,m/s$ at an angle of $ 120^\circ$ with the direction of flow of water. The speed of water in the stream, is

• A. 0.25 m / s
• B. 0.5 m/s
• C. 1.0 m/s
• D. 0.433 m/s

Answer 1

Answer: (A)

The component of velocity of man in opposite direction of the flow is $0.5 \times \operatorname{Cos}\left(180^{\circ}-120^{\circ}\right)=$ $0.25\, m / s$
so the velocity of flow(stream) will also be $0.25 \,m / s$
so that the person can oppose the stream and in result he will not be drifted by the stream and will reach directly
opposite side.