A swimmer can swim with speed '$v$' with respect to still water in a river which is flowing with speed $u$. There is a float moving with the river. Now the swimmer overtakes float and gets a lead of $l$ and returns back to the float. Time taken by swimmer in this process will be
A swimmer can swim with speed '$v$' with respect to still water in a river which is flowing with speed $u$. There is a float moving with the river. Now the swimmer overtakes float and gets a lead of $l$ and returns back to the float. Time taken by swimmer in this process will be
- A
$\frac{{2l}}{v}$
- B
$\frac{{2l}}{u}$
- C
$\frac{l}{{\sqrt {{v^2} - {u^2}} }}$
- D
$\frac{l}{{v + u}} + \frac{l}{{v - u}}$
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