A swimmer can swim in still water at of 10 ms-1 While crossing a river

1.	A swimmer can swim in still water at of 10 ms-1 While crossing a river his average speed is 6 ms-1 . If he crosses the river in the shortest possible time, what is the speed of flow of water?(a) 16 ms-1 (b) 4 ms-1 (c) 60 ms-1 (d) 8 ms-1
Answer» (d) The resultant velocity of swimmer must be perpendicular to speed of water to cross the river in a shortest time ∴ \( v^2_S = v^2 +v^2_w\) \(v^2_w = v^2_s -v^2\) =100-36 = 64 ∴ V = 8 m/s^-1

A swimmer can swim in still water at of 10 ms-1 While crossing a river his average speed is 6 ms-1 . If he crosses the river in the shortest possible time, what is the speed of flow of water?(a) 16 ms-1 (b) 4 ms-1 (c) 60 ms-1 (d) 8 ms-1

Answer»

(d) The resultant velocity of swimmer must be perpendicular to speed of water to cross the river in a shortest time

∴ \( v^2_S = v^2 +v^2_w\)

\(v^2_w = v^2_s -v^2\) =100-36 = 64

∴ V = 8 m/s^-1

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A swimmer can swim in still water at of 10 ms-1 While crossing a river his average speed is 6 ms-1 . If he crosses the river in the shortest possible time, what is the speed of flow of water?(a) 16 ms-1 (b) 4 ms-1 (c) 60 ms-1 (d) 8 ms-1

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