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# The current in the river is 1.0m/s.A woman swims 300m down stream and then back to her starting point without stopping.If she can swim $2.0m/s$ is still water,determine the time required for the round trip.

$\begin{array}{1 1}400s\\100s\\200s\\300s\end{array}$

Down stream :
$\overrightarrow{V}_{PS}=\overrightarrow{V}_{PW}+\overrightarrow{V}_{WS}$
$\Rightarrow V_{PS}=2.0+1.0$
$\Rightarrow V_{PS}=3.0m/s$
$x=vt$
$\Rightarrow t=100s$
Upstream :
$\overrightarrow{V}_{PS}=\overrightarrow{V}_{PW}+\overrightarrow{V}_{WS}$
$\Rightarrow V_{PS}=2.0+(-1.0)$
$\Rightarrow V_{PS}=1.0m/s$
$x=vt$
$\Rightarrow t=300s$
$\Rightarrow$ time =100+300=400s