Can you help me with this question re Ghosts

LOL!

They (supposedly - I do not believe they exist really) move along what were familiar routes for their living, corporeal form. So if someone goes and moves a doorway, the ghost disappears at the door's original location now solid wall, or appears in the room from that point. Floors are normally left on their original levels.

There is a ghost story about a stretch of ancient road somewhere in England, I forget where, but one of many first established by the Romans. 'Tis said (so must be true) that this particular part is haunted by a unit of Roman troops apparently wading waist-deep through the ground. They are "really" marching along their original road surface, which became buried over the time since to that depth. So 'tis said... never let reality obstruct a good story!

LOL! Maybe they are just going through the motions of walking and are actually floating across the floor.

Presumably, that wall wasn't there when they were alive. But the floor was.

I do recall a ghost story, about an American Navy vessel that was decommissioned and turned into a museum. Somewhere in the states. Tours would go through and a couple of them had been led by a Blonde haired young serviceman. Trouble is, there was nobody like that on the payroll, and he looked a lot like the guy who died on that ship during WW2.

Maybe when they suddenly appear they have risen from the floor/ground

Supposed to be a interdimensional thing.

Not the same physics as here. Why they have troubles moving things.

Think of it this way, try moving around blindfolded. Not as easy as many think. Yet still possible.

Because they only happen in the imagination so they're capable of doing anything you can imagine.

I get this question all of the time 👻

They have no weight.

Because they can fly.