That Kids ask! - 7yr olg G/son asked (after watching "Star-Trek"), If the Astronauts on the Space Station coud build a long pipe in space, and gently stick one end into Earths Air, would it all be sucked out into space? - I gave him what I thought to be a satisfying answer, "It would need a very long pipe, probably over 50miles long, and it would be so heavy they wouldn't be able to move it" - "it's in SPAAACE Grandad! it wouldn't weigh anything!" - too smart kids these days!
P.S What IS the answer (just so I actually know)
|
|
Don't know if they'll be able to get their heads round it but air is being pulled to the earth by gravity like everything else - putting a pipe around it won't change that.
|
Nope.
Just scale it up and imagine a napkin ring thousands of miles across dropped onto North America. No reason why the air should decide to abandon the Earth at that point, so why would it escape down a hosepipe?
Suppose you could demo it with some food colouring, a bucket, a transparent straw and an orange, but be vary of capillary action ruining your point. :-)
Also... when kids ask questions like that a truly fascinating site is what-if.xkcd.com (book too).
|
Try this one:
If you build your pipe so that it stops about 30 feet up , would air flow up it?
No, you might say.
Now re-name your pipe a "chimney". is there not a draught up it at the bottom?
|
>> Now re-name your pipe a "chimney". is there not a draught up it at the bottom?
Not necessarily in my experience, although wind can cause a draught (and sometimes a reverse draught by blowing down the chimney).
However if you put a heat source - a fire for example - at the base of the chimney, the draught will be there almost immediately and will be steady once the chimney becomes warm or hot. Of course there can be badly designed chimneys and contrary winds.
|
>>Now re-name your pipe a "chimney". is there not a draught up it at the bottom?
Only if there's a fire lit. Hot air rises.
|
|
Big temp difference (and pressure difference) between ground level air and air at 50 miles up, would drive air rapidly up the spout. Self-powered exhaust ventilation! Assuming a space-hook to hang said spout from.
|
>> Big temp difference (and pressure difference) between ground level air and air at 50 miles
>> up, would drive air rapidly up the spout. Self-powered exhaust ventilation! Assuming a space-hook to
>> hang said spout from.
Wouldn't work, the chimney (spout) would be cold half way up conducting heat away from gases, they would then be cold and you would get a gas blockage.
|
SQ. Try not quoting everything
>> Wouldn't work, the chimney (spout) would be cold half way up conducting heat away from
>> gases, they would then be cold and you would get a gas blockage.
>>
Try cascara.
Last edited by: VxFan on Sun 12 Apr 15 at 04:51
|
It appears that seemingly simple questions can have seemingly complex answers, asked same Q at "watering hole" tonight, "Fred", quite a knowledgeable soak suggested that Newton may be right when he Stated that "Nature abhors a vacuum, and would naturally seek to fill it". I just "googled" that and Wiki has an interesting opinion, although I would need a degree to understand it! - Anyway he's gone home now so I can't wait for next weeks!
P.S Me thinks the "chimney! analogy soots me best!
|
Think about it. If the vacuum could pull the air out, it would've done so by now, there's nothing stopping it!
Air is dense, it's got mass and gravity sticks it to the surface. That's why your car's got a maximum speed, it's pushing all that dense stuff aside.
|
>>
>> Wouldn't work, the chimney (spout) would be cold half way up conducting heat away from
>> gases, they would then be cold and you would get a gas blockage.
>>
It works in traditional arab houses in north Africa - air pipes.
|
>> It works in traditional arab houses in north Africa - air pipes.
It does, because the bottom (inside the house) is cooler and the top (outside and the chiney) is hotter.
In with an earth to space chimney its the other way round.
If you have a log burner you will know that if you have a long stove pipe, the whole pipe needs to be hot before you get a good draught.
Last edited by: VxFan on Sun 12 Apr 15 at 18:55
|
>>the whole pipe needs to be hot before you get a good draught.
Not really, it's all about speeding up the airflow, by opening the vents/valves, and even the doors slightly if neccessary, in a multi-fuel stove - similar to the way a venturi in a carburettor speeds up airflow.
The reason y'all want a hot flue is to stop the moisture in wood condensing on the flue wall and creating tar.
|
>> >>Now re-name your pipe a "chimney". is there not a draught up it at the
>> bottom?
>>
>> Only if there's a fire lit. Hot air rises.
>>
No, there's often a draught from an unlit chimney.
But you are right, heat is the answer. Not necessarily from a fire, but because the house wall is at an average 24-hour temperature, and daytime temperature even in an unheated house will often be higher.
|
>> No, there's often a draught from an unlit chimney.
Only when there is enough wind to blow over the top creating a vortex and subsequent low pressure area at the top.
No wind in space
Last edited by: VxFan on Sun 12 Apr 15 at 18:54
|
Gravity keeps the atmosphere on the earth's surface, as noted several times. No fundamental reason why that should change if there is a pipe around it.
Quite possible though that some odd temperature gradients could create unexpected effects. "Weather" is largely the result of temperature differentials in the atmosphere. The pipe could have its own, with rain, snow and hail in there.
All rather academic until skyhooks are invented. You'd also need them at intervals along the pipe - there is probably no material that could support its own weight for anything like the length between the surface and the near-vacuum of sub-space, whether hung from the top or standing on the ground.
|
>> All rather academic until skyhooks are invented. You'd also need them at intervals along the
>> pipe - there is probably no material that could support its own weight for anything
>> like the length between the surface and the near-vacuum of sub-space, whether hung from the
>> top or standing on the ground.
Firstly the space pipe could only be constructed and installed at the poles, anywhere else would cause the space pipe to wrap round the earth as it rotates. That means the guy ropes would have to be anchored to land masses at the equator. Even then they might not be wide enough apart and flying buttresses would need to be installed.
|
SQ for the person who couldn't be bothered
>> Even then they might not be wide enough apart and flying buttresses would need to be
>> installed.
:)
I was just thinking the poles would be best. If the tube could be made very light, and a comparatively large mass such as a very heavy space station attached the the top, then the length/height could be tuned so as to put the mass into a geostationary orbit. That would put the tube length at around 22,000 miles though which could be a challenge, but at least there is a very near vacuum at that height.
Last edited by: VxFan on Sun 12 Apr 15 at 18:56
|
Another bonus...if you were to anchor the space station at the top of the tube, you could then have a spiral staircase round its interior wall.
This would save the need for expensive rockets with their exhaust pollution and also give the astronauts much needed exercise before a long spell of inactivity.
Win..win !
|
>>I was just thinking the poles would be best
I meant the equator of course
|
|
Yeah, but what about the centrifugal force of that thing whirling round and round?
|
>> Yeah, but what about the centrifugal force of that thing whirling round and round?
which is why you build the space pipe at the poles, the world spins around it. It will oscillate slightly due to the earths wobble tho.
Last edited by: Zero on Sun 12 Apr 15 at 16:10
|
>> Yeah, but what about the centrifugal force of that thing whirling round and round?
What about it?
Do you have trouble standing up, because the earth is rotating under your feet at 1000mph? (Well, a bit less in Surrey than at the equator I suppose, but people live there too).
The column of air is also there now, just without the tube.
|
>> >> Yeah, but what about the centrifugal force of that thing whirling round and round?
>>
>> What about it?
>>
>> Do you have trouble standing up, because the earth is rotating under your feet at
>> 1000mph?
No,but that is because I am not 500 miles tall with my feet on earth and my head near and under the gravitational effect of the moon. I accept that the gyroscopic effect should be at play here, but being 500 miles high my head will detach from my body traveling as it is in excess of 17,000 miles per hour. Much better to build my space pipe on the axis of rotation.
|
The speed of your noddle in a synchronous orbit 500 miles above the surface would be about 1110 mph if that helps your calcliations so no need to worry about it flying off. In any case your neck would be subject to much the same forces so it and your head stay happily together.
With respect to the earth of course it would be stationary.
|
>>I meant the equator of course
Proposed by Arthur C Clarke in his book 3001.
Enough diamond material was recovered from the detonation / implosion of Jupiter to build diamond towers in to space and construct a habitable ring around the world.
Space elevators would use electricity to launch spacecraft from Earth using linear induction and some of the electricity could be recovered in the decent stage.
He worked out the sums to place geostationary satellites in 1945 - though he did have a first in mathematics.
Of course we now have carbon nano tubes with exceptional strength and Graphene so who knows?
Last edited by: zippy on Sun 12 Apr 15 at 18:20
|
>>
>> Only when there is enough wind to blow over the top creating a vortex and
>> subsequent low pressure area at the top.
>>
You don't need a wind, you don't even need a pipe.
If the air at ground level is heated, as on a summer day, then it will tend to rise to displace cooler air higher up.
Of course a wind across the chimney pot may help, or sometimes hinder if in an unfortunate direction with regard to roofs etc.
|
Here's the latest one for you to ponder! ;-) (asked by G.Child).
If Comets brought Water to earth, and no Comets have hit Earth for millions of years, does that mean that the water we are drinking now is exactly the same stuff that the Dinosaurs drank, or does Earth now manufacture it's own new water?
My answer: As long as it contains at least 4% Alcohol I'm not really bothered! (but that's because I'm not really sure!~)
|
Haha I like that one and I don't know the answer. My immediate thought was yes, it's the same stuff but of course it breaks down and is reconstituted.
A scientific type will be along soon I'm sure :-)
|
Not much, but in that glass of water, there's good chance one molecule was in Queen Cleopatra's bath...
|
Where I live the water comes out of the tap, it goes through the sewage works and into the river. Down river it's pumped up into the reservoir which feeds my tap.
Where I live the water comes out of the tap............................................................
|
>> Not much, but in that glass of water, there's good chance one molecule was in
> Queen Cleopatra's bath...
That's a thought provoking post Slidingpillar.
Teacher at school once asked us to calculate the number of atoms of Oxygen in each breath we took were exhaled in Horatio Nelson's last breath.
Ignoring take-up by plants and oxidisation it turned out to be around 5 atoms.
|
Here's one for you!
{Oldies, I suspect :-) }
"Why is a mouse when it spins?"
|
>> "Why is a mouse when it spins?"
The higher the fewer, and sometimes the when!
|
|
Didn't Cleopatra bathe in Asses milk...:......no water or molecules thereof involved surely.
|
|
in case you are asked Ass milk is approximately 86.348756% water (dependant on breed)
|
Don't you just love people who give an approximation to six decimal places:-)
|
|
If you have wine made from grapes, and you drink 5 glasses, have you had your 5 a day?
|
|
Yes but you should take a malt supplement. My favourite is Laphroaig
|
>>My favourite is Laphroaig
Mine too, discovered here www.queenshead.com/ 30 years ago.
|
I seem to have developed a fetish for malts beginning in A....Just looked and have 4, including Ardbeg. Cheers, Hic.
|
|
Lagavulun (sp?) has given me many a headache. Very peaty but quite drinkable.
|
|
I also have a liking for Islay (and West coast) whisky. My favourite was Port Ellen, sadly closed many years ago.
|
|
Coincidentally was in Waitrose today and they have the ten year old for £25 reduced from £35.
|
Have a large one for me will you CG.
That pub I mentioned up thread is also where I 'discovered' Pendle Witches, Old Peculiar, Harveys,
Shepherd Neame, Adnams, Everards, Goachers, Marstons, Wadworths, Brakspears,
and a whole host of other proper-decent ales - Happy Daze!
|
>If you have wine made from grapes, and you drink 5 glasses, have you had your 5 a day?
Wasn't there a question in Scientific American years ago where someone asked if the nutritional value of Guinness was as good as they claimed "Would it be possible to survive on a diet of Guinness alone"?
I think that the answer was "Yes. but you would need to drink 80 pints per day to get your daily requirement of (something)."
Last edited by: Kevin on Thu 30 Mar 17 at 23:54
|
A CONVERSATION WITH THE DOCTOR
Q: Doctor, I've heard that cardiovascular exercise can prolong life; is this true?
A: Your heart is only good for so many beats, and that's it... don't waste them on exercise. Everything wears out eventually. Speeding up your heart will not make you live longer; that's like saying you can extend the life of your car by driving it faster. Want to live longer? Take a nap.
Q: Should I cut down on meat and eat more fruits and vegetables?
A: You must grasp logistical efficiencies. What does a cow eat? Hay and corn. And what are these? Vegetables. So a steak is nothing more than an efficient mechanism of delivering vegetables to your system. Need grains? Eat chicken. Beef is also a good source of field grass (green leafy vegetable). And a pork chop can give you 100% of your recommended daily allowance of vegetable products.
Q: Should I reduce my alcohol intake?
A: No, not at all. Wine is made from fruit. Brandy is distilled wine, that means they take the water out of the fruity bit so you get even more of the goodness that way. Beer is also made out of grain. Bottoms up!
Q: How can I calculate my body/fat ratio?
A: Well, if you have a body and you have fat, your ratio is one to one. If you have two bodies, your ratio is two to one, etc.
Q: What are some of the advantages of participating in a regular exercise program?
A: Can't think of a single one, sorry. My philosophy is: No Pain...Good!
Q: Aren't fried foods bad for you?
A: YOU'RE NOT LISTENING!!! .... Foods are fried these days in vegetable oil. In fact, they're permeated in it. How could getting more vegetables be bad for you?
Q: Will sit-ups help prevent me from getting a little soft around the middle?
A: Definitely not! When you exercise a muscle, it gets bigger. You should only be doing sit-ups if you want a bigger stomach.
Q: Is chocolate bad for me?
A: Are you crazy? HELLO! Cocoa beans! Another vegetable!!! It's the best feel-good food around!
Q: Is swimming good for your figure?
A: If swimming is good for your figure, explain whales to me.
Q: Is getting in-shape important for my lifestyle?
A: Hey! 'Round' is a shape!
Well, I hope this has cleared up any misconceptions you may have had about food and diets.
|
Awkward Questions - Robin O'Reliant
