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Author Topic: If we Built a Building BIG enough, could we sense Earth's rotation?  (Read 17299 times)

Offline Seany

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If we Built a Building Big enough...

Would we be able to feel the rotation of the earth??

« Last Edit: 06/04/2008 00:28:51 by chris »


 

Offline neilep

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Now why d'ya wanna go and make the Earth into A Ping Pong bat ?








...bear in mind we'd have to use up half the Earth to make the materials for it !!


 

Offline Seany

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Now why d'ya wanna go and make the Earth into A Ping Pong bat ?







...bear in mind we'd have to use up half the Earth to make the materials for it !!




Yes.. Now it does look like a ping pong bat.. :P

Well.. I was just wondering.. Would it still be long enough for us to feel the rotation of the earth?
 

Offline neilep

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Have ewe really drawn it to scale  ?


The top three quarters will be in outer space and will be dull and boring....they'll have no atmosphere !! *le groan* ;D ;D
 

Offline Seany

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Have ewe really drawn it to scale  ?


The top three quarters will be in outer space and will be dull and boring....they'll have no atmosphere !! *le groan* ;D ;D

Maybe not to scale!! But how tall would it have to be for us to feel the rotation?
 

Offline neilep

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Have ewe really drawn it to scale  ?


The top three quarters will be in outer space and will be dull and boring....they'll have no atmosphere !! *le groan* ;D ;D

Maybe not to scale!! But how tall would it have to be for us to feel the rotation?

LOL...I refer this question to people who actually can let ewe know !!

...as much as I luff playing at being klevur I need too many lucozade tablets to maintain the illusion that I actually know something !!
 

Offline Seany

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LOL LOL...

But do you think we could ever feel the rotation, however high the building was?.. Or would the speed of rotation have torn the building apart?
 

Offline neilep

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LOL LOL...

But do you think we could ever feel the rotation, however high the building was?.. Or would the speed of rotation have torn the building apart?

LOL *help....he's still asking me klevur stuff*

*swallows a whole bottle of the glucose drink and a handful of glucose tablet chasers*

I think......the building would not be torn apart unless it was so tall it hit the moon !!....as far as feeling the rotation....well...put it like this...it would still take 24 hours to make one rotation !....I think it would be slight if at all !!


*gawwwd help me that I hope I made some sense*

LOL
 

Offline Make it Lady

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If you could feel the earth's rotation wouldn't it be good to put a revolving restaraunt at the top of the tower block. That would make you so giddy.
 

Offline Seany

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LOL LOL...

But do you think we could ever feel the rotation, however high the building was?.. Or would the speed of rotation have torn the building apart?

LOL *help....he's still asking me klevur stuff*

*swallows a whole bottle of the glucose drink and a handful of glucose tablet chasers*

I think......the building would not be torn apart unless it was so tall it hit the moon !!....as far as feeling the rotation....well...put it like this...it would still take 24 hours to make one rotation !....I think it would be slight if at all !!


*gawwwd help me that I hope I made some sense*

LOL

But the circumference  is much bigger!
 

Offline neilep

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LOL LOL...

But do you think we could ever feel the rotation, however high the building was?.. Or would the speed of rotation have torn the building apart?

LOL *help....he's still asking me klevur stuff*

*swallows a whole bottle of the glucose drink and a handful of glucose tablet chasers*

I think......the building would not be torn apart unless it was so tall it hit the moon !!....as far as feeling the rotation....well...put it like this...it would still take 24 hours to make one rotation !....I think it would be slight if at all !!


*gawwwd help me that I hope I made some sense*

LOL

But the circumference  is much bigger!


"Hi There,

Sheepy can not come to the forum right now cos he has expired after an overdose of Lucozade. Please leave a message for Klevur peeps to answer ."





 

Offline Seany

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LOL LOL...

But do you think we could ever feel the rotation, however high the building was?.. Or would the speed of rotation have torn the building apart?

LOL *help....he's still asking me klevur stuff*

*swallows a whole bottle of the glucose drink and a handful of glucose tablet chasers*

I think......the building would not be torn apart unless it was so tall it hit the moon !!....as far as feeling the rotation....well...put it like this...it would still take 24 hours to make one rotation !....I think it would be slight if at all !!


*gawwwd help me that I hope I made some sense*

LOL

But the circumference  is much bigger!


"Hi There,

Sheepy can not come to the forum right now cos he has expired after an overdose of Lucozade. Please leave a message for Klevur peeps to answer ."







LOL LOL..  Very cute dead sheepy ;)

OK Neil. I shall wait ;)
 

another_someone

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Rather depends on where you built the building - putting a tower block over the north pole (maybe the south pole might be on firmer ground) would have no effect on caused by the rotation of the Earth at all that would not be noticable at ground level.

I am assuming your project is to be on the equator.

Indeed, building up would both reduce the effect of gravity, and increase the effects of rotation; but given that the surface of the Earth is already over 6,000Km above the centre, and the atmosphere is only about 120Km thick (the top of mount Everest is only about 8.5Km up), so to build to the edge of space would still only add about 2% to the distance between the the top of the building and the centre of the Earth.

More interesting would be that as you build up, you would have longer hours of daylight.
 

Offline neilep

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Seany............if you build it, they will come  !



Hmmm...you may not know what I'm referring too !!

*quick quiz*...who does ?
 

Offline Seany

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Rather depends on where you built the building - putting a tower block over the north pole (maybe the south pole might be on firmer ground) would have no effect on caused by the rotation of the Earth at all that would not be noticable at ground level.

I am assuming your project is to be on the equator.

Indeed, building up would both reduce the effect of gravity, and increase the effects of rotation; but given that the surface of the Earth is already over 6,000Km above the centre, and the atmosphere is only about 120Km thick (the top of mount Everest is only about 8.5Km up), so to build to the edge of space would still only add about 2% to the distance between the the top of the building and the centre of the Earth.

More interesting would be that as you build up, you would have longer hours of daylight.

That is very interesting!!
 

Offline Seany

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Seany............if you build it, they will come  !



Hmmm...you may not know what I'm referring too !!

*quick quiz*...who does ?

I do not get it.. LOL
 

Offline Soul Surfer

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what do you mean by "feel the rotation of the earth".  If you mean like sitting on a roundabout going round fast enough you get pushed away from the centre.  Sometimes called the centrifugal force.

The answer is you can "feel" it now if you have a spring balance that is sensitive enough.  You don't need a tall building to get you further from the centre.  If you measure a weight at (or near) the pole and then take it to the equator and measure the same weight again it will be a bit less on the spring balance because of the extra centrifugal force.  If you used a lever balance with weights it would not show any difference because the weights would be affected in exactly the same way.

If by feel you mean sense an effect on your body it is very unlikely unless you went right out into space and orbited the earth when you would probably notice that you were in zero gravity because in an orbiting satellite the attraction of the earth is exactly balanced by the centrifugal force of the orbit.

Now if you built a really tall structure on the equator and went so far out that the centrifugal force balanced the weight of the structure  you could build a "space elevator".  Such structures have been proposed and may just be possible using the very strongest materials on a planet like the earth.
 

Offline Seany

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But to make a "Space elevator" wouldn't you need like half the materials in the Earth??

And yes, I do mean "feel" as in the roundabout movement thing..

Thanks for the detailed answer!
 

Offline Soul Surfer

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No  the suggestion is that it should be a strip of carbon fibre material in tension only a metere or two wide a few centimetres thick and about 35 thousand miles long
 

lyner

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It may be worth pointing out that, on the top of the building, you would still be going around in a circular path so there would be no 'pulsing force'. Eveything on the Earth would be rotating round the centre of mass of Earth plus building. By effectively altering the shape of the Earth you would have shifted the CM a tiny bit. (A REALLY tiny bit!)
 

Offline Seany

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If the building was 35km tall.. And I was on the toppest floor in a room.. would I be stuck onto one side of the room, because of the earth rotating?
 

lyner

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Quote
If by feel you mean sense an effect on your body it is very unlikely unless you went right out into space and orbited the earth when you would probably notice that you were in zero gravity because in an orbiting satellite the attraction of the earth is exactly balanced by the centrifugal force of the orbit.
There is only one distance at which the forces exactly balance out and that distance is the distance of the satellite's centre of mass.  That is the only distance at which the gravitational attraction is exactly what is needed to produce the appropriate central force to keep the craft in its orbit. On parts of the satellite away from the Earth, there is a small net  force 'outwards' and on parts on the side of Earth there is a small net force 'inwards'. What you really have, in an orbiting craft, is microgravity and not zero gravity.
This is the same effect that causes two tidal bulges of the seas around the Earth.
If your satellite were very flexible, it would stretch in the same way, making it elongated along the radius of the orbit; wierd.
 

lyner

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If the building was 35km tall.. And I was on the toppest floor in a room.. would I be stuck onto one side of the room, because of the earth rotating?
No -  there is no tangential acceleration - you are going in a circle at uniform speed. You would just 'feel' a bit lighter. 35km wouldn't be anything like enough to get a different measure of weight. You could measure the difference in G field, though, through general relativistic  effects on time (search on the Mossbauer effect, for instance).
« Last Edit: 06/04/2008 21:37:10 by sophiecentaur »
 

Offline Seany

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How much less would you weigh?
 

Offline graham.d

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Look up Foucault's pendulum. There is one in the Pantheon in Paris and I remember there used to be one in the science museum in London. This senses the earth's rotation. Also, as mentioned in the question on tides, in the Northern hemisphere, the tidal range on North facing coasts is higher than on South facing coasts because of the Coriolis force.

On the tall building (at the equator) issue, the downward force (your weight) gets less as you ascend the building. This is only partly due to you moving away from the earth and gravity getting less as a result, but also due to it being balanced by you being in orbit. When you get to a height of about 35,786 km above the earth (I know that is quite a tall building) you will be in a geostationary orbit and you will be weightless.
 

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