A boat man could row his boat with a speed 10 m / sec . He wants to take his boat from P to a point Q just opposite on the other bank of the river flowing at a speed 4 m / sec . He should row his boat

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A boat man could row his boat with a speed 10 m / sec . He wants to take his boat from P to a point Q just opposite on the other bank of the river flowing at a speed 4 m / sec . He should row his boat -

TestHub · Accepted Answer

To reach point Q directly opposite, the boat's resultant velocity must be perpendicular to the river flow. Let $v_{b}$ be boat speed and $v_{r}$ be river speed. The boat must be rowed at an angle $θ$ upstream such that $v_{b} sin θ = v_{r}$ .

$sin θ = \frac{v _{r}}{v _{b}} = \frac{4}{10} = \frac{2}{5}$ . So, $θ = sin^{- 1} (\frac{2}{5})$ upstream.

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