# Inertia over an airplane [duplicate]

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When an airplane is traveling, it moves at the same speed as the earth does due to inertia, but since, the plane is not directly touching the globe, how does is the speed of the earth is associated with the plane so that they move at the same speed? (not taking into account some fenomena or the force the motors generate

## marked as duplicate by Qmechanic♦Apr 24 '18 at 8:28

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## 1 Answer

The atmosphere rotates at pretty much the same speed as the Earth. The plane is pushed by the atmosphere so that its speed and the Earth's remain associated.

• And how is the atmosphere associated to the earth itself? By earth y mean just the globe, by gravity? Thank you – Angelixus Apr 24 '18 at 6:13
• The atmosphere is kept near the Earth's surface by gravity, but that's not really relevant to this question, since gravity can't by itself cause rotation where there was none before. Suppose the atmosphere was stationary and the Earth rotated. Then the surface features of the Earth, like mountains and forests (or really anything that sticks out above the Earth's surface), would push the lower atmosphere until it was rotating at the same speed as the Earth. The lower atmosphere and upper atmosphere mix, so eventually the whole atmosphere would be rotating at the same speed as the Earth. – probably_someone Apr 24 '18 at 6:45
• It's the same thing that makes your fan work: objects moving through air have to push the air out of the way, unless it's moving at the same speed that they are. – probably_someone Apr 24 '18 at 6:47
• But in reality, the atmosphere was never really stationary; it was either here when the planet formed, which meant that it was likely rotating at about the same speed as all of the other material that formed the Earth, or it came from emissions from the Earth's crust and oceans (and life), in which case it rotates with the Earth by inertia, since the objects that emitted it were rotating. – probably_someone Apr 24 '18 at 7:06