A swimmer, capable of swimming at a speed of 1.81 m/s in still water (i.e., the swimmer can swim with a speed of 1.81 m/s relative to the water), starts to swim directly across a 2.29-km-wide river. However, the current is 1.31 m/s, and it carries the swimmer downstream. (a) How long does it take the swimmer to cross the river? (b) How far downstream will the swimmer be upon reaching the other side of the river?

2 answers

Tan A = 1.31/1.81 = 0.72376.
A = 35.9o

Tan 35.9 = d/2.290.
d1 = 2.290*Tan35.9 = 1.658 km downstream.

sin35.9 = 1.31/V2.
V2 = 1.31/sin35.9 = 2.23 m/s

d2 = sqrt(2.29^2+1.66^2) = 2.83 km =
Distance across with wind.

d2 = V2*t = 2830 m.
2.23*t = 2830.
t = 1269 s. = 21 Min. to cross.
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