system
Given the following post, respond as if you're commenting on Reddit:
human
How fast would one need to accelerate a container of air to make it bunch up to one side, creating a vacuum on the other?

Back when railroads were new, alarmists feared that the speed of the carriages going as fast as 20mph would create a deathly situation for the passengers.  This was obviously quite wrong.  But how quick of an acceleration WOULD be needed to start heaving the air in a contained space over to one side of it?
gpt
For something like a planet with an atmosphere, you can define what's called a *scale height* which is the height at which the density is reduced to 36%. For planets, the simplest expression is h=kT/mg where m is the mass of the molecule, g is the gravitational field strength, k is Bolztmann's constant and T is the temperature. For Earth, this is roughly the height of Mt. Everest.

For a train you can replace g with the acceleration, and if you want h to be 10 meters, the acceleration would to be about 1700 g's.