Question

At what altitude above the earth's surface is the gravitational acceleration 5. 6 m/s2?.

Answer 1

a = G M / R^2    gravitational acceleration

R^2 = G M / a = 6.67E-11 * 5.98E24 / 5.6 m^2/s^2

R^2 = 6.67 * 5.98 / 5.6 E13 = 71.2E12

R = 8.44E6 m

H = (8.44 - 6.37) E6 m = 2.07E6m   above the surface of the earth

(About 1/3 of the radius of the earth)

As a check 4/3^2 = 1.78

9.8 m/s^2 / 1.8 = 5.4    Close enough to 5.6