Two swimmers A and B start swimming from different positions on the same bank as shown in figure. The swimmer A swims at angle 90° with respect to the river to reach point P. He takes 120s to cross the river of width 10m. The swimmer B also takes the same time to reach the point P.

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Velocity of B along Y-axis with respect to earth is 1/ 3m/ s .

Velocity of A with respect to river is 1/ 6m/ s .

River flow velocity is 1/ 4m/ s .

Velocity of B along X-axis with respect to earth is 5/ 24m/ s .

answer is B, D.

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Detailed Solution

For A, $t = \frac{d}{V_{MR}} \Rightarrow 120 = \frac{10}{V_{MR}}$
$\begin{array}{l} \Rightarrow V_{MR} = \frac{1}{12} m / s \\ Drift = V_{R} t \\ 30 = V_{R} (120) \Rightarrow V_{R} = \frac{1}{4} m / s \end{array}$
For B,
Along Y-axis, $S_{y} = u_{y} t + \frac{1}{2} a_{y} t^{2}$
$\begin{array}{ll} \Rightarrow 10 = u_{y} (120) \\ \Rightarrow u_{y} = \frac{1}{12} m / s \end{array}$