Chapter 7, Problem 34ICA

In many engineering uses, the value of "g," the acceleration due to gravity, is taken as a constant. However, g is actually dependent upon the distance from the center of the Earth. A more accurate expression for g is:

     $g=g_0{\left(\frac{R_e}{R_e+A}\right)}^2$

Here, g₀ is the acceleration of gravity at the surface of the Earth, A is the altitude above the Earth's surface, and R_e, is the radius of the Earth, approximately 6,380 kilometers [km]. Assume g₀ = 9.8 meters per second squared [m/s²]. What is the value of g at an altitude of 20 miles [mi] in units of meters per second squared (m/s² )?