The speed of a swimmer is 4,km,h^{-1} in stil | vedclass

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(A) Let the width of the river be $w = 1\,km = 1000\,m$. The speed of the swimmer in still water is $v_{sm} = 4\,km\,h^{-1}$.Since the swimmer swims n

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(A) Let the width of the river be $w = 1\,km = 1000\,m$. The speed of the swimmer in still water is $v_{sm} = 4\,km\,h^{-1}$.Since the swimmer swims normal to the river flow,the time taken to cross the river is $t = \frac{w}{v_{sm}} = \frac{1\,km}{4\,km\,h^{-1}} = 0.25\,h$.During this time,the swimmer is carried downstream by the river current. The drift $x$ is given as $750\,m = 0.75\,km$.The drift is caused by the river velocity $v_r$,so $x = v_r 	imes t$.Substituting the values: $0.75\,km = v_r 	imes 0.25\,h$.Therefore,$v_r = \frac{0.75}{0.25} = 3\,km\,h^{-1}$.The speed of the river water is $3\,km\,h^{-1}$.

The speed of a swimmer is $4\,km\,h^{-1}$ in still water. If the swimmer makes his strokes normal to the flow of a river of width $1\,km$,he reaches a point $750\,m$ downstream on the opposite bank. The speed of the river water is $.........\,km\,h^{-1}$.

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