system
Given the following post, respond as if you're commenting on Reddit:
human
would a flag on a flying spaceship flap or would it stay in the same position?

sorry for the badly worded question, but I'm half cut and will forget my question by the morning :)
gpt
It would move during the initial acceleration, not due to the passage of air (as flags do on earth) but due to inertia while the ship is being accelerated. 

If you think of the direction of acceleration as "up", then during acceleration the flag would hang "down", lagging behind the ship. Incidentally the occupants of the ship are subject to the same inertia and would experience the acceleration as if it was a gravitational pull downwards.

When the acceleration stops, the flag would move again, as tension in the material is no longer being opposed, pulling the flag towards the mast. When the ship is not accelerating, internal friction will slow the movement of the flag until it is still.