Question

The drag force F (in pounds) of water on a swimmer can be modeled by F = 1.35s^2 where s is the swimmers speed (in miles per hour). How fast must you swim to generate a drag force of 10 pounds?

Answer 1

We are given

$F=1.35s^2$

where

F is the drag force (in pounds) of water on a swimmer

s is the swimmers speed (in miles per hour)

we are given

F=10

so, we can set it and then we can solve for s

$10=1.35s^2$

$1.35s^2\cdot \:100=10\cdot \:100$

$135s^2=1000$

$\frac{135s^2}{135}=\frac{1000}{135}$

$s^2=\frac{200}{27}$

$s=\sqrt{\frac{200}{27}},\:s=-\sqrt{\frac{200}{27}}$

Since, speed can never be negative

so, we will only consider positive value

$s=\frac{10\sqrt{6}}{9}$

$s=2.72166mph$..............Answer