The thing that brings my attention is the phrase “without any initial relative velocity against the planet”. They might not move relative to the planet, but Earth is not an inertial reference frame and is rotating, so bodies in different latitudes would have different speeds in relation to an inertial referential.
The thing that brings my attention is the phrase “without any initial relative velocity against the planet”. They might not move relative to the planet, but Earth is not an inertial reference frame and is rotating, so bodies in different latitudes would have different speeds in relation to an inertial referential.
This might give some ideas to someone. But not very directly, I think.