• AnIndefiniteArticle@sh.itjust.works
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    25 days ago

    Let’s convert to metric so we can tell.

    15 ft is about 5 m.

    Water pressure increases by 10,000 pa per meter (rhogh, rho=1000 kg/m^3, g~10m/s^2), so total pressure is 50 kpa, or 1/2 earth atmospheric pressure.

    One side of that hole has ambient pressure of 1 atm. The other side has that plus water pressure totalling 1.5 atm.

    A pressure is just an energy density. Multiply by the cross-sectional area of the interface to get the energy gradient across the interface. An energy gradient is a force. We don’t have a measure of the cross-sectional area of the hole, but if we expect a person to fit through let’s call it 1m^2.

    50 kpa = 50 kJ/m^3, so total force felt across this opening is 50kN which is the equivalent weight of five metric tons.

    Size of the hole absolutely matters. If it’s only the size of a fist (10cm x 10cm) then instead of 5 metric tons it’s only 50 kg of equivalent weight, or about the weight of a person and easily survivable.