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A person crosses a river along the path ab and again returns to a through same path a river flows with speed u and person 's speed with respect to water is v if the path ab makes an along theta with river flow then find the ratio of time to cross the river from a to b and to return to a from b to a?pls do not spam genuine answers are welcomed spamed accounts will be reportedthx in advance |
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Answer» Answer: a. Velocity of man with respect to river water, V=5kmh −1 . This is greater than the river flow velocity. Therefore, he can cross the river directly (along the shortest path or no drift condition from flow velocity). The angle of swim, θ= 2 π
+sin −1 ( v u
) =90 o +sin −1 ( v u
) =90 o +sin −1 ( 5 3
)=90 o +37 o =127 o w.r.t. the river flow or 37 o w.r.t. the perpendicular in upstream DIRECTION b. Resultant velocity or velocity of mass will be v m
= v 2 −u 2
= 5 2 −3 2
=4kmh −1
In the direction perpendicular to the river flow. c. time taken to cross the river t= v 2 −u 2
d
= 4kmh −1
1km
= 4 1
h=15min |
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