For a flow through a smooth pipe, the Fanning friction factor $(f)$ is given by $f=mRe^{-0.2}$ in the turbulent flow regime, where $Re$ is the Reynolds number and $m$ is a constant. Water flowing through a section of this pipe with a velocity $1\:m/s$ results in a frictional pressure drop of $\:10 kPa$. What will be the pressure drop across this section (in $kPa$), when the velocity of water is $\:2 m/s$?

1. $11.5$
2. $20$
3. $34.8$
4. $40$