Physics/pressure question about opening a door underwater?

I know that in order to open a door underwater, the pressure inside needs to match the outside by water filling the air cavity so that the pressure is equal on both sides.

If water covered the door fully or by a few feet, would you be able to open the door before the whole room was filled with water?

This question is for a sci-fi story I'm writing based on the beginning of Subnautica if anyone is concerned 😂

2 Answers

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  • 1 month ago

    Let us give a few values.  Water 1m deep on the outside of a 1m wide door.  Atmospheric pressure inside.  The average pressure is 1/2 m depth of water or 5000 N/m^2 giving a force on the 1m^2 opening of 500 kg weight.  if the depth was down to 30cm then the force is equivalent to 50 kg weight so you should be able to open the door if the depth of water is under 30 cm.  Much deeper and it would be beyond your strength.

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  • Anonymous
    1 month ago

    What matters is opening a valve letting sea water enter the room in such a way outer pressure is brought inside and inner and outer pressure are perfectly balanced. 

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