Diving Physics

Another unit is the bar, where 1 bar equals 14.5 psi. A value of 1 bar is very close to the air pressure on Earth. The atmospheric pressure of the air around you is now likely to be 14.5 psi. (Yes, I said “most likely” because I don’t want to judge you. You’re probably reading this from the top of Mount Everest, where the pressure is only 4.9 psi, because there’s less air above you pushing down. If so, send me a picture. ) in terms of force and area, it is equal to 100,000 newtons per square metre.

Water is also made up of small moving particles that act like balls, and these particles collide with underwater objects (such as humans), creating pressure. water him many More particles of the same volume of air, which means there are more collisions to produce more pressure. But just like going to the top of Mount Everest decreases air pressure, deeper into the water Increases pressure, because gravity pulls the water molecules down. For every 10 meters of depth, the pressure increases by 1 bar, or 14.5 pounds per square inch. This means that when diving 20 meters (about 60 feet) below sea level, there will be a water pressure of 43.5 psi, three times the air pressure at the Earth’s surface.

(The fact that pressure increases with depth prevents all of the ocean water from collapsing into an infinitely thin layer. Since pressure is greater the deeper you go, the water below pushes up more than it pushes the water above it down. This difference is compensated for by the downward force of gravity, so The water level remains constant.)

43.5 psi may seem like too much for a person to handle, but it’s actually not that bad. Human bodies are highly adaptable to changes in pressure. If you’ve been to the bottom of a pool, you already know the answer to this pressure problem—your ears. If the water pressure on the outside of your eardrum is greater than the air pressure inside your inner ear, the membrane will expand and can really hurt. But there is a nice trick to fix this: if you force air into the middle ear cavity by closing your nose while trying to get air out of it, the air will be forced into that cavity. With more air in the inner ear, the pressure on both sides of the membrane will be equal and you will feel normal. This is called “equivalence” for reasons that I hope are clear.

There is actually another air space that you need to equalize while you are diving – inside your scuba mask. Don’t forget to add air to it as you go deeper, otherwise this thing will squash your face awkwardly.

There is another physical error a diver can make. It is possible to create a closed air space in your lungs by holding your breath. Suppose you hold your breath at a depth of 20 meters and then move to a depth of 10 metres. The pressure inside your lungs will remain the same during this ascent, because you have the same lung volume, and they contain the same amount of air. However, the water pressure outside it will decrease. Decreased external pressure on your lungs makes them appear to be excessively inflated. This can cause a tear in the lung tissue, or even force air into the bloodstream, which is officially bad.


There’s another problem to deal with when you’re underwater: floating and sinking. If you want to stay underwater, it pays to sink rather than float – up to a point. I don’t think anyone wants to sink to such depths that they never come back. Also, it’s nice to be able to float when you’re on the surface. Fortunately, divers can change their “buoyancy” for different situations. This is called buoyancy control.

Things go down when the downward force of gravity is greater than the upward force of buoyancy. If these two forces were equal, the object would be neutrally floating and would neither rise nor descend. It’s like hovering, but in the water, and that’s basically what you want to do when diving.

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