Our moon with atmosphere?

[FBM]

Question- If you were on the inside wall of a collossal rotating cylinder and fired an arrow straight up (that is, through or toward the rotational axis) where would it come down?....Where it was fired from?...Or does it depend how 'high' it were fired?

It depends. Do you mean standing on one of the poles, at the equator, or somewhere between? I think you get slightly different answers depending on which you mean. If you're on a pole and the moon has no wobble or wind, it should come straight back down. If you're at the equator shooting straight up from the center of mass, it should come down straight behind you. Between the poles and equator, though, you would have to work it out with trig and calculus or something, which I can't even begin to do.

[mistermack]

Can't we just sheath the moon inside a large balloon and then inflate it with gasses?

One problem with that, is that the pressure needed to pop a balloon is inversely proportional to it's diameter. It's much easier to pop a big one, than a tiny one.
And the diameter of the Moon is pretty big.
So the balloon would pop with just the tiniest pressure inside. And anyway, rubber doesn't stretch when it's deep frozen. It just shatters.

[Robert_S]

Question- If you were on the inside wall of a collossal rotating cylinder and fired an arrow straight up (that is, through or toward the rotational axis) where would it come down?....Where it was fired from?...Or does it depend how 'high' it were fired?

It depends. Do you mean standing on one of the poles, at the equator, or somewhere between? I think you get slightly different answers depending on which you mean. If you're on a pole and the moon has no wobble or wind, it should come straight back down. If you're at the equator shooting straight up from the center of mass, it should come down straight behind you. Between the poles and equator, though, you would have to work it out with trig and calculus or something, which I can't even begin to do.

You guys play Bumble Puppy for keeps!

[Gawdzilla Sama]

On the inside of a cylinder, firing at the axis, the arrow would have the force of the bow working one way, and the spin of the cylinder working another. The resultant vector would be a sum of those actions.

Now, for fun, what would the archer see the arrow do?

[Mysturji]

We should just build the smokestacks of our coal-fired plants high enough that they vent directly to space. That should solve the problem.

Um, no. The gases wouldn't have escape velocity, so they'd re-enter after a while.

But by that time, we'll be further along in our orbit. We will have left the gases behind.

Really, this can work.

Um, escape velocity...

Escape velocity is only applicable if you're going ballistic.
Didn't you see "The Mouse on the Moon"?
Travel straight up from Earth's surface at a constant 1 MPH, and eventually you will escape.
So all we is a big fan at the bottom of each smokestack.

[Gawdzilla Sama]

We should just build the smokestacks of our coal-fired plants high enough that they vent directly to space. That should solve the problem.

Um, no. The gases wouldn't have escape velocity, so they'd re-enter after a while.

But by that time, we'll be further along in our orbit. We will have left the gases behind.

Really, this can work.

Um, escape velocity...

Escape velocity is only applicable if you're going ballistic.
Didn't you see "The Mouse on the Moon"?
Travel straight up from Earth's surface at a constant 1 MPH, and eventually you will escape.
So all we is a big fan at the bottom of each smokestack.

Think about that.

[Mysturji]

Um, escape velocity...

Escape velocity is only applicable if you're going ballistic.
Didn't you see "The Mouse on the Moon"?
Travel straight up from Earth's surface at a constant 1 MPH, and eventually you will escape.
So all we is a big fan at the bottom of each smokestack.

Think about that.

Adding orbital velocity by keeping the same geographical location directly beneath you would make "eventually" much shorter, but it's not necessary if you have enough time and patience. Earth isn't the only thing in space with gravity. Eventually, you will stray into another gravity well.
Edit: fix quotes.

[Gawdzilla Sama]

But the gases wouldn't have the escape velocity to start with, and no means of increasing their speed. Gravity would decay them back to Earth in due time, and they'd have to go through the ozone layer to get there.

[Clinton Huxley]

All you need is several trillion trillion tonnes of "slow air". It's too lazy to reach escape velocity.

[mistermack]

But the gases wouldn't have the escape velocity to start with, and no means of increasing their speed. Gravity would decay them back to Earth in due time, and they'd have to go through the ozone layer to get there.

Only for a short smoke stack. If the smoke stack was long enough to reach geostationary orbit distance, the gases would just keep orbiting the Earth without falling back. If it was even longer, they would float away.
That's because they have the velocity of the spin of the Earth.

The smokestack would in effect be a space elevator.

Might cost a bit to build though.

[Gawdzilla Sama]

But the gases wouldn't have the escape velocity to start with, and no means of increasing their speed. Gravity would decay them back to Earth in due time, and they'd have to go through the ozone layer to get there.

Only for a short smoke stack. If the smoke stack was long enough to reach geostationary orbit distance, the gases would just keep orbiting the Earth without falling back. If it was even longer, they would float away.

The smokestack would in effect be a space elevator.

Might cost a bit to build though.

Remember that a "space elevator" can't be too long, and that distance, IIRC, isn't long enough for your project.

Plus we'd be pumping our atmosphere into interplanetary space. Baby-bathwater.

[mistermack]

Remember that a "space elevator" can't be too long, and that distance, IIRC, isn't long enough for your project.

Plus we'd be pumping our atmosphere into interplanetary space. Baby-bathwater.

You'd have to put more carbon into the atmosphere to power the pumping, than you would get rid of.
I don't think it's a good idea.

[Gawdzilla Sama]

Remember that a "space elevator" can't be too long, and that distance, IIRC, isn't long enough for your project.

Plus we'd be pumping our atmosphere into interplanetary space. Baby-bathwater.

You'd have to put more carbon into the atmosphere to power the pumping, than you would get rid of.
I don't think it's a good idea.

True, pumping would be necessary, the gases would slow down due to contact with the cold "stack" as well. Pumping against a column of gases hundreds of miles long, a fluid gas column, would be a bit difficult.

And 90% of stack gases is plain old air.