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Is it possible to create a completely sealed room where a door can't be opened?

  1. Apr 26, 2012 #1
    Hi, this is my first post here so mods, if my question would be better directed somewhere else, please do tell me.

    My knowledge of physics is only up till high school so I would greatly appreciate it if I could have your opinion on the following hypothetical situation:

    Is it possible to create a completely sealed room (say, 4m by 4m by 3m) with a pressure so high such that you cannot move a door which opens inwards, into the room?

    - Which physics theories would apply to this situation? I could only think of the combined gas law.
    - What is the theoretical temperature which is required to generate this pressure? Assuming that an adult would be the person to open the door?

    Thank you.
     
  2. jcsd
  3. Apr 26, 2012 #2
    You could use a pump but it would never remove all the air completely.I also think that the pressure would rip the door to shreds anyway.
     
  4. Apr 26, 2012 #3
    Thanks for replying!

    I'm thinking of a situation where the pressure inside the room is so high compared to the pressure outside the room, that a person wouldn't be able to open the door inwards. In that case, a pump to completely remove the air within the room wouldn't be necessary, right? Would that still be possible?
     
  5. Apr 26, 2012 #4

    russ_watters

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    Staff: Mentor

    Sounds like an airplane to me!

    Thing is, it requires very little pressure. It can happen in a poorly (airflow) balanced room/building.

    Just take the force you want the door to resist, multiply by 2 and divide by the area to get the pressure needed.
     
    Last edited: Apr 26, 2012
  6. Apr 26, 2012 #5
    What would the pressure difference between the inside of the room and the outside realistically be?

    Also, in an airplane, the temperature difference between the interior of the plane and its environment varies by more than just a few degrees Celcius, doesn't it?
     
  7. Apr 26, 2012 #6

    Dale

    Staff: Mentor

    It doesn't take much pressure. A typical door is about 8 ft by 4 ft, which is about 4000 square inches. So even 0.5 psi would take about 1 ton of force to open.
     
  8. Apr 26, 2012 #7

    russ_watters

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    Staff: Mentor

    ... And temperature difference isnt relevant here unless you are trying to generate the pressure with heating.
     
  9. Apr 26, 2012 #8
    Let's say a heater is placed within the room to increase the pressure. How much more would the temperature need to increase in a room that is 4m by 4m by 3m?
     
  10. Apr 26, 2012 #9

    phinds

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    To do WHAT?
     
  11. Apr 26, 2012 #10
    The temperature outside an airplane is often at arctic temperatures like -50C.
     
  12. Apr 27, 2012 #11
    this sounds like a suicide project

    clearly, higher temp = more pressure but dont try raising temp to seal a door. like stated earlier, poor ventilation will have the biggest effect by creating a vaccuum in your room. youd need to pair this with an extremely windy day lol

    if its truly 100% sealed, lets just say youd be hurting your body before you use temperature to seal the door.

    think of a car's cooling system if youre good with automotive at all. the coolant in a car usually operates from 185-210* F and thats around 13-16psi. its a lot of pressure but your heater wont go up to those temps

    and you cant just think of sealing a room, raise temp and base pressure off that. your walls are going to sponge/transfer the heat so even if you use the right temp and math to get the pressure, reality will prove your numbers wrong
     
  13. Apr 27, 2012 #12
    This effect can actually be seen in real life. For example, it is impossible to open a car door underwater (with human strength) without winding down the windows, because the pressure of the water outside is bigger than the pressure of the air inside. This effect is magnified by the fact that you can't compress liquids.
     
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