I need to find the value of acceleration of gravity 3000 miles above the earths surface. I figured 3000 miles = 4.83 x 10^3 meters. Mass of the earth equals 5.98 x 10^24kg. I used the equation: g= GM/r^2 and get 17.1 m/s^2. This is too high a value. I don't think I am using the correct distance in my calculation. Any help Please?