13.3.3—G is approximately constant for small changes in height near the Earth’s

Although g=GM/r² varies with distance from Earth’s centre, the change is negligible over small everyday height ranges, so g≈9.8 m s⁻² is a useful approximation.

Use the constant-g model for local motion and mg∆h calculations, but switch to inverse-square reasoning for satellites or large altitude changes.

A building’s roof and ground have almost the same g compared with a spacecraft thousands of kilometres away.

“Constant near Earth” is an approximation, not evidence that the gravitational field has no spatial dependence.