What is the acceleration of gravity at a height of 6400 km above the Earth's surface?

At a height of 6400 km above the Earth's surface, the acceleration due to gravity can be calculated using the formula ( g' = g_0 \left( \frac{R}{R + h} \right)^2 ), where ( g_0 ) is the acceleration of gravity at the Earth's surface (approximately 9.81 m/s²), ( R ) is the Earth's radius (about 6400 km), and ( h ) is the height above the surface. Substituting the values, the effective gravity at this height is approximately 2.45 m/s². This demonstrates that gravity decreases with altitude, being significantly weaker at that height compared to the surface.