Answer
$8.0\times10^{8}\,J$
Work Step by Step
The gravitational force on the satellite from the planet is centripetal.
Therefore, we can write
$\frac{mv^{2}}{r}=80\,N$
Kinetic Energy= $\frac{1}{2}mv^{2}=\frac{1}{2}\times r\times \frac{mv^{2}}{r}$
$=\frac{1}{2}\times 2.0\times10^{7}\,m\times80\,N= 8.0\times10^{8}\,J$
