Editing Openai/6945b8b5-5788-8000-9352-d5062c255aa0 (section)

==== 2. The decisive point (this cannot be bypassed) ====

A plane’s 500 mph is measured relative to the air, not relative to Earth’s axis or space.

That means:
* Eastbound flight: Plane = (air’s eastward speed) + 500 mph
* Westbound flight: Plane = (air’s eastward speed) − 500 mph

But the destination land is also moving eastward at the same base speed as the air.

So the only speed that matters for closing the distance is:

: ±500 mph relative to the destination

The rotation direction cancels out because it is shared.