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Author Topic: Why can't we use the earth's rotation to travel?  (Read 7601 times)

Nena Blake

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Why can't we use the earth's rotation to travel?
« on: 09/09/2009 11:30:03 »
Nena Blake  asked the Naked Scientists:
   
Hi Guys
 
I have a question...
 
Bearing in mind that the earth revolves every 24 hours, if I wanted to travel from, say, England to Australia, why cant I float up into the sky and 12 hours later float down into Australia?  Thus saving about 12 hours flying time and huge amounts of fuel!
 
I am sure there is a simple explanation as otherwise we would be doing it or is it possible with a bit of ingenuity?
 
Thank you
 
Nena Blake
"There's always another way of looking at things......."

What do you think?


 

Offline RD

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Why can't we use the earth's rotation to travel?
« Reply #1 on: 09/09/2009 12:16:46 »
The jetstream is used to assist East-West aircraft travel, (the jetstream is in part caused by Earth's rotation).
« Last Edit: 09/09/2009 12:20:35 by RD »
 

lyner

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Why can't we use the earth's rotation to travel?
« Reply #2 on: 09/09/2009 13:26:55 »
People had a lot of trouble with this idea when Scientists told them that the Earth was revolving and that Sun was at the centre.
There were a lot of comments like - "Why doesn't the wind blow us all over?" etc. "Riding on a horse, even, you feel a wind in your face so how could we all be moving so fast?"
The fact is that the place you're standing, plus you and all the air around you are all moving around at the same speed. If you "floated up", there would be nothing to slow you down - you'd still be going along at the same speed as the ground you left. Newton observed this a long time ago and it isn't at all obvious - until you travel in a plane and it feels as if you are stationary (when it's not bumpy) when you are doing 500mph.
One time the Earth's rotation does help is when they launch rockets into orbit. They always launch then in an Easterly direction because they can use the 'forward' motion to give them some free momentum.
As RD says, there are large bodies of air, very high up, which are being stirred up due to convection currents and the Earth's motion. It is possible to use them - in the same way as you can use the trade winds etc. etc. for sailing  but the first bit I wrote is the simplest (?) explanation.
« Last Edit: 09/09/2009 13:28:31 by sophiecentaur »
 

Offline graham.d

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Why can't we use the earth's rotation to travel?
« Reply #3 on: 09/09/2009 13:35:53 »
The atmosphere is largely whizzing around the earth with the earth's rotation. The trade winds and the Jet stream result from the forces involved (Coriolis forces in particular) because of the earth's rotation. The atmosphere is a very thin layer compared with the earth's radius so floating up a few miles would not change your speed relative to the earth, even with no atmosphere. Floating up would mean you still have the "horizontal" velocity imparted by the earth's rotation.
 

Offline wanhafizi

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Why can't we use the earth's rotation to travel?
« Reply #4 on: 09/09/2009 15:33:43 »
Momentum...

While we are standing on the earth's surface, we have the same velocity as the earth does, even if we don't feel it.

The momentum is still being conserved event if we float like a balloon.

If the earth suddenly stop rotating, you'll feel like being inside a car when the emergency break is applied.
 

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Why can't we use the earth's rotation to travel?
« Reply #4 on: 09/09/2009 15:33:43 »

 

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