The Naked Scientists
  • Login
  • Register
  • Podcasts
      • The Naked Scientists
      • eLife
      • Naked Genetics
      • Naked Astronomy
      • In short
      • Naked Neuroscience
      • Ask! The Naked Scientists
      • Question of the Week
      • Archive
      • Video
      • SUBSCRIBE to our Podcasts
  • Articles
      • Science News
      • Features
      • Interviews
      • Answers to Science Questions
  • Get Naked
      • Donate
      • Do an Experiment
      • Science Forum
      • Ask a Question
  • About
      • Meet the team
      • Our Sponsors
      • Site Map
      • Contact us

User menu

  • Login
  • Register
  • Home
  • Help
  • Search
  • Tags
  • Member Map
  • Recent Topics
  • Login
  • Register
  1. Naked Science Forum
  2. Non Life Sciences
  3. Physics, Astronomy & Cosmology
  4. How much energy is required to create absolute vacuum in one cubic meter?
« previous next »
  • Print
Pages: [1]   Go Down

How much energy is required to create absolute vacuum in one cubic meter?

  • 5 Replies
  • 7406 Views
  • 0 Tags

0 Members and 1 Guest are viewing this topic.

Offline thedoc (OP)

  • Forum Admin
  • Moderator
  • Hero Member
  • *****
  • 510
  • Activity:
    0%
  • Thanked: 17 times
    • View Profile
How much energy is required to create absolute vacuum in one cubic meter?
« on: 18/07/2015 07:50:02 »
harshad gulannavar asked the Naked Scientists:
   
How much energy is required to create absolute vacuum in one cubic meter.
What do you think?
« Last Edit: 18/07/2015 07:50:02 by _system »
Logged
 



Offline syhprum

  • Naked Science Forum King!
  • ******
  • 5061
  • Activity:
    8%
  • Thanked: 64 times
    • View Profile
Re: How much energy is required to create absolute vacuum in one cubic meter?
« Reply #1 on: 16/07/2015 22:00:45 »
To condense every last particle of gas in a one cubic meter chamber a cold sink would have to be maintained for an indefinite time and or a getter fired as in CRT,s  despite thermal leakage.
To remove EVERY particle would take an infinite time and energy.
« Last Edit: 19/07/2015 11:37:27 by syhprum »
Logged
syhprum
 

Offline chiralSPO

  • Global Moderator
  • Naked Science Forum King!
  • ********
  • 3434
  • Activity:
    12.5%
  • Thanked: 428 times
    • View Profile
Re: How much energy is required to create absolute vacuum in one cubic meter?
« Reply #2 on: 16/07/2015 22:50:48 »
It is not possible to create "absolute vacuum" in a box of any size.

Given a box that was substantially larger than one cubic meter, and ignoring quantum effects for the moment, one could reduce the number of particles in the box to the point where a given cubic meter of it probably has no particle in it at any given point in time (but this would take a lot of energy, and is of limited utility).
Logged
 

Offline evan_au

  • Global Moderator
  • Naked Science Forum King!
  • ********
  • 8969
  • Activity:
    75%
  • Thanked: 882 times
    • View Profile
Re: How much energy is required to create absolute vacuum in one cubic meter?
« Reply #3 on: 18/07/2015 04:04:09 »
Atmospheric pressure at sea level is about 10.2 tonnes per square meter, or about 100kN of force on a square meter.

In "Physics Land" (ie everything behaves in an ideal manner), assume that you have a square tube with a 1m x 1m hole, open at one end, and a perfectly-fitting square plug that can move along the square tube. To produce a cubic meter of vacuum, you just need to pull the plug out by 1 meter.

Now, Energy=Force x Distance=100x103N x 1m = 100kJ.

Of course, as other respondents have noted, there is no such thing as a perfect seal, moving a plug is likely to scrape off atoms (and larger lumps), and there is no material which has zero vapour pressure. So the above is a "best possible" answer. 
« Last Edit: 18/07/2015 04:24:32 by evan_au »
Logged
 

Offline syhprum

  • Naked Science Forum King!
  • ******
  • 5061
  • Activity:
    8%
  • Thanked: 64 times
    • View Profile
Re: How much energy is required to create absolute vacuum in one cubic meter?
« Reply #4 on: 19/07/2015 11:36:25 »
It would be interesting to know how much power is expended per cubic meter to maintain the near perfect vacuum in the LHC
As far as I can ascertain the refrigeration system of the LHC consumes 170 KW to maintain 9000 cubic meters of vacuum which equate to about 19w/m^3 of course the initial pump down from atmospheric pressure would have required a considerable amount of energy.
« Last Edit: 19/07/2015 12:01:54 by syhprum »
Logged
syhprum
 



Offline PmbPhy

  • Naked Science Forum King!
  • ******
  • 3903
  • Activity:
    0%
  • Thanked: 125 times
    • View Profile
Re: How much energy is required to create absolute vacuum in one cubic meter?
« Reply #5 on: 20/07/2015 02:05:41 »
Quote from: evan_au on 18/07/2015 04:04:09
Atmospheric pressure at sea level is about 10.2 tonnes per square meter, or about 100kN of force on a square meter.

In "Physics Land" (ie everything behaves in an ideal manner), assume that you have a square tube with a 1m x 1m hole, open at one end, and a perfectly-fitting square plug that can move along the square tube. To produce a cubic meter of vacuum, you just need to pull the plug out by 1 meter.

Now, Energy=Force x Distance=100x103N x 1m = 100kJ.

Of course, as other respondents have noted, there is no such thing as a perfect seal, moving a plug is likely to scrape off atoms (and larger lumps), and there is no material which has zero vapour pressure. So the above is a "best possible" answer.
Nice response, Evan. I was going to post the exact same thing. Great minds think alike! :)
Logged
 



  • Print
Pages: [1]   Go Up
« previous next »
Tags:
 

Similar topics (5)

What are "energy" and "work" ?

Started by The ChampBoard Physics, Astronomy & Cosmology

Replies: 108
Views: 53634
Last post 31/12/2018 20:54:40
by yor_on
What is Kirlian photography and Kirlian Energy?

Started by neilepBoard General Science

Replies: 2
Views: 7250
Last post 27/04/2007 15:02:27
by Karen W.
What really is dark energy and dark matter?

Started by Diogo_Afonso_LeitaoBoard Physics, Astronomy & Cosmology

Replies: 5
Views: 6345
Last post 08/09/2017 12:01:01
by puppypower
What are dark matter and dark energy?

Started by ijazBoard General Science

Replies: 5
Views: 6799
Last post 21/01/2016 12:43:52
by alysdexia
MOVED: Dark Motion, does it link to Dark Energy and Dark Matter?

Started by Colin2BBoard Technology

Replies: 0
Views: 667
Last post 29/08/2020 16:46:16
by Colin2B
There was an error while thanking
Thanking...
  • SMF 2.0.15 | SMF © 2017, Simple Machines
    Privacy Policy
    SMFAds for Free Forums
  • Naked Science Forum ©

Page created in 0.266 seconds with 50 queries.

  • Podcasts
  • Articles
  • Get Naked
  • About
  • Contact us
  • Advertise
  • Privacy Policy
  • Subscribe to newsletter
  • We love feedback

Follow us

cambridge_logo_footer.png

©The Naked Scientists® 2000–2017 | The Naked Scientists® and Naked Science® are registered trademarks created by Dr Chris Smith. Information presented on this website is the opinion of the individual contributors and does not reflect the general views of the administrators, editors, moderators, sponsors, Cambridge University or the public at large.