Gravitational Potential energy question

[MasterAsia]

Homework Statement

a 5.00 x 10^2 kg satelilite is in circular orbit 2.00 x 10^2 km above Earth's surface. calculate

a) gravitaional potential energy which i got, which is -3.13 x 10^10 J
b) kinetic energy of the satellite
c) binding energy of satellite
d) the percentage increase in launching energy required for the satellite to escape earth

Homework Equations

2GM/c^2

Eg = - GMem/re

The Attempt at a Solution

v = sqroot GM/r for the velocity then using the equation 1/2mv^2 to get the Ek, but i don't know how to get the radius so i can plug it into the Ek equation.

 

[Lok]

The Earth has a radius of 6000 km.

 

[K^2]

How did you get the gravitational potential without knowing the radius?

2GM/c^2

That's Schwarzschild Radius. That is not a relevant equation for this problem.