Gravity and Height: Find the Height of a Physics Problem

[NIZBIT]

I have a problem like the one below:

https://www.physicsforums.com/showthread.php?t=114812

I understand how they derived it(I did the same thing) but never say what is the height. So could someone tell what the height is?

 

[Chi Meson]

In that problem, height is relative to the radius of the planet. The correct answer for THAT question should have been
r = \sqrt{2}*R.
That would be the orbital radius. The "height" would be the altitude above the planet, which would be
(\sqrt{2}*R)-R
or(\sqrt{2}-1)*R
Which happens to be equal to 0.41*R

Substitute the radius of the planet in for R and you get the "height."

 

[NIZBIT]

Ok I see now. Wasn't so obvious last night.