Hi

I'm helping a friend with some homework he forgot to do and there was one question we got stuck on - wondering if I could get any help?

The ISS Orbits the Earth with an orbit of mean radius 6.8x10^6 m.

Use "V(grav) = -(GM) / r"

to show that the gravitational potential difference between the Earths surface and the position of the ISS is given by equation 2:

"delta V(grav) = GM (1/rE - 1/r)"

Where rE is the radius of the Earth, r is the radius of the orbit, G is the gravitational force constant and M the mass of the Earth.

Effectively, it is a very difficult equation re-arrangement.

Any help would be great.

Thanks