Given that temperature is a measure of kinetic energy and the earth is moving very quickly. How can we get temperatures

Question: Given that temperature is a measure of kinetic energy and the earth is moving very quickly. How can we get temperatures very close to absolute zero on Earth?

Asked by freddie to Adam, Rob, Sheila, Suzie on 24 Mar 2011 in Categories: General.

Suzie Sheehy answered on 23 Mar 2011:

Hi Freddie, another good question!
You sure have a lot of questions

The Earth is protected by our atmosphere, so all the air around us is moving at the same speed as the Earth… so in terms of friction causing heat that isn’t a problem.

In terms of the total energy of the system, you have to consider just our frame of reference I think. So in that sense you can remove energy from the system to get down near to absolute zero.

An interesting question though, I hadn’t thought of it before…

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Adam Tuff answered on 23 Mar 2011:

How that’s a head scratcher! I think it has to do with either our intertial frame, in that you can have things with no apparent kinetic energy relative to yourself – I’m not 100% sure!

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Sheila Kanani answered on 24 Mar 2011:

We can recreate the right conditions and use cryogenics and vacuums to get temperatures close to absolute zero on Earth.

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freddie commented on 23 Mar 2011:

But if you had a single particle floating in a vacuum vibrating very quickly, it would have KE and therefore temperature – but there wouldn’t be any friction.

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- Suzie commented on 23 Mar 2011:
  
  yep and you could remove the energy from it and get it down to absolute zero… Adam made a good point – that in our frame of reference we can have particles with almost no energy and therefore near absolute zero… but maybe in another frame they are moving so have more energy? This is a good one… and I don’t really know the answer!
  
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doppler commented on 23 Mar 2011:

Is temperature to do with the average speed of the *particles* within an object, rather than its velocity compared to another macroscopic object? I’m having difficulty thinking about temperature in terms of velocity of a macroscopic object, as this would make it dependent on what we are measuring that object’s velocity relative to, which would mean the temperature would be different depending on your viewpoint… :-S E.g to me, the Earth appears to be staying still…

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- Suzie commented on 24 Mar 2011:
  
  yes I think that’s a good way of viewing it – I think that is what I was struggling to think about as well – temperature is directly related to the mean kinetic energy of the particles in a system relative to the centre of mass of that system.
  
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