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A person swims in a river aiming to reach exactly on the opposite point on the bank of a river. His speed of swimming is $0.5 \mathrm{~m} / \mathrm{s}$ at an angle of $120^{\circ}$ with the direction of flow of water. The speed of water is
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$0.25 \mathrm{~m} / \mathrm{s}$
Let the speed of water $=\overrightarrow{\mathrm{u}}$
Speed of swimmer $=\overrightarrow{\mathrm{v}}=0.5 \mathrm{~m} / \mathrm{sec}$
Angle between $\overrightarrow{\mathrm{v}}$ and $\overrightarrow{\mathrm{u}}$ is $120^{\circ} .$ Then
$\sin \theta=\frac{\overrightarrow{\mathrm{u}}}{\overrightarrow{\mathrm{v}}} \Rightarrow \frac{\mathrm{u}}{0.5}=\frac{1}{2}$ or $\mathrm{u}=0.25 \mathrm{~ms}^{-1}$
Speed of swimmer $=\overrightarrow{\mathrm{v}}=0.5 \mathrm{~m} / \mathrm{sec}$
Angle between $\overrightarrow{\mathrm{v}}$ and $\overrightarrow{\mathrm{u}}$ is $120^{\circ} .$ Then
$\sin \theta=\frac{\overrightarrow{\mathrm{u}}}{\overrightarrow{\mathrm{v}}} \Rightarrow \frac{\mathrm{u}}{0.5}=\frac{1}{2}$ or $\mathrm{u}=0.25 \mathrm{~ms}^{-1}$
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