2
Question
The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which he should make his strokes with respect to the north, is given by
The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which he should make his strokes with respect to the north, is given by
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Solution
The correct option is A 30∘ west
Given:
Speed of swimmer w.r.t river, VSR=20 m/s
Speed of river flow, VRG=10 m/s
From above diagram,
→VSG=→VSR+→VRG
So,
sinθ=|→VRG||→VSR|
sinθ=1020=12
∴θ=30∘
Hence, option (A) is the right choice.
Given:
Speed of swimmer w.r.t river, VSR=20 m/s
Speed of river flow, VRG=10 m/s
From above diagram,
→VSG=→VSR+→VRG
So,
sinθ=|→VRG||→VSR|
sinθ=1020=12
∴θ=30∘
Hence, option (A) is the right choice.
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