Joose asks strange physics questions again!

[Joose]

I have a peculiar physics conundrum. Well, I'm actually pretty sure of the answer, just wondering if I've missed something obvious.

Imagine a fictional place that is basically an infinitely large sky. It goes on forever, and every part of it (somehow) has approximately normal earth sea level atmosphere and has 1G of gravity. In it, place a city sized building, aerodynamic enough to stay stable and upright as it plummets constantly downwards, and built out of something strong enough that it doesn't tear itself to pieces or set on fire from friction or anything like that. Other than the above, everything works on completely real world physics.

If you were to wake up inside the city, assuming it had been around long enough to reach its terminal velocity, would you know it was falling? Also assuming its sealed up so there's no draft and sufficiently soundproofed that you cant hear the rushing wind outside, that is. My initial thought was that you would be weightless, like in the vomit comet, but then I realised that the vomit comet works by the acceleration of it plunging downwards counteracting the acceleration due to gravity. Once the city gets to its terminal velocity it wouldn't be accelerating any more, so you would be able to walk about inside and it would feel completely normal. Unless you stepped outside of course.

Is that right? Anyone think of a reason how someone inside might be able to twig that the whole thing is in a state of free-fall?

[Dr. kitteny berk]

Some fucktard will get pissed off with being just a touch too hot, jimmy the window and break the city.

[Joose]

"Im just going to let in some fresh air..."
"NOOOOOOOOOOOOOOOOOOOOOO"
*whooooooooosh*

[Grimmie]

I remember reading somewhere that if you were to theorhetically become concious during a lift moving up or down, you wouldn't be able to tell the direction you were moving.

Presumably the same could be said for your city - you'd feel some sort of inertia, but you'd be hard pressed to know if it was falling or rising. Everything else would be falling at a relative rate too.

[Dr. kitteny berk]

I think the way you're thinking about this makes it more complicated than it is, mr joose.

If we ignore gravity, because you have no source for it, basically you're describing an object that has thrust (hence the movement) and people in it.

We call those planes, admittedly it's a fucking huge massive plane, that's plummeting, rather than flying but nonetheless, a plane is the easiest thing to compare your city to.



And with planes, pretty much once at speed/altitude, the only things that give the fact you're moving away on a plane is visual stuff, and bastard turbulence when you're trying to sleep.

So yeah, your city will be rocked randomly by inexplicable earthquakes, thus confusing scientists.

[Joose]

This is an excellent point. It is basically just a plane going in a funny direction. That makes it a lot simpler to think about.

As for the earthquakes: I've been in light aircraft and I have been in bloody great passenger jets, and the difference in how much turbulence the two experience is massive. If you continue scaling that up to something the size of a city and you would need the wind outside to be really significant before people inside could feel it. Not saying it would never happen, but it would be something you tracked with a calendar rather than a clock. I don't think the occasional light earthquake would spoil the illusion completely. Possibly enough to make the more inquisitive scientists think "huh, this place sure does get a lot of earthquakes", but let's be honest, anyone sealed inside a glob shaped city isn't going to need much in the way of inquisitiveness to figure out something is up eventually.

[HereComesPete]

If the city is at terminal/settling velocity then all horses being equal (which I believe is the intent?) then I would say there would be no earthquake type activity as those ripples that may affect the falling plane would be absorbed through sheer mass of object as to be indistinguishable from your normal movement. Normal horse (as alluded to by Grimmie's lift example) would be balanced so you wouldn't perceive any change in your weight unless a horse was introduced/removed or modified.

I do question the gravity source however as potentially an unconstrained constant as opposed to a general reciprocal attraction to another object exerting its own gravitational horse (if we're going with Newton on this) may well result in other horses exerting a free-fall or weightless state when coupled with the other parameters that affect the falling city, but removing centrifugal/centripetal and Coriolis type horses renders a state where something entirely unexpected may be the norm, people with bones may well not exist on the city as the horses make any dense organic matter explode, or they could turn in to hat stands.

The falling cat problem is a good read for a similar type of physics puzzle.

[Dr. kitteny berk]

I fucking love the swear felcher.

[fabyak]

If the city is effectively a closed system I can't see the speed itself being a problem as your speed relative to your surroundings would be 0. I don't think you would notice it happening narf as you only tend to feel the horses of acceleration or changes in direction (yeah I know, that's a different type of acceleration) so unless something out of the ordinary happens I don't think you'd spot it. Fuck knows what speed we're barrelling through the universe at but I don't notice it.

Tldr: horses

[HereComesPete]

many horses involved in this!

[Joose]

Im now trying to picture a coriolis horse.