Answer
Additional power needed:$P_{k}=77.78kW$
If the mass reduces: $P_{k}=38.89kW$
Work Step by Step
In this case we are working with kinetic velocity, the kinetic power will be:
$P_{k}=\frac{W_{k}}{t}=\frac{\frac{1}{2}m\Delta V^2}{t}$
$P_{k}=\frac{\frac{1}{2}1400kg*(110\frac{km}{h}*(\frac{1000m}{1km})*(\frac{1h}{3600s}))^2-(70\frac{km}{h}*(\frac{1000m}{1km})*(\frac{1h}{3600s}))^2}{5s}$
$P_{k}=77.78kW$
If the mass reduces:
$P_{k}=\frac{\frac{1}{2}700kg*(110\frac{km}{h}*(\frac{1000m}{1km})*(\frac{1h}{3600s}))^2-(70\frac{km}{h}*(\frac{1000m}{1km})*(\frac{1h}{3600s}))^2}{5s}$
$P_{k}=38.89kW$
