The resistive force on an aeroplane flying in a horizontal plane is...

The resistive force on an aeroplane flying in a horizontal plane is given by $\mathrm{F}_{\mathrm{f}}=\mathrm{kv}^2$, where k is constant and v is the speed of the aeroplane. When the power output from the engine is $\mathrm{P}_0$, the plane flies at a speed $\mathrm{v}_0$. If the power output of the engine is doubled the aeroplane will fly at a speed of