Depth pressure question

[justreadingposts]

Hello, I am not a diver at all. A bunch of us were talking and have a question. In the even that a person dived into a grain silo above ground. Let's say the silo was 110 ft tall and filled with water. Would you experience pressures just like as if you had dove 110ft below the surface of the ocean?

 

[bygolly]

Yes...if the silo was filled with salt water though.

 

[cloudflint]

yes, though freshwater dosent excert as much pressure per ft as salt water since salt water is heavier. If you think about it there is no difference between diving in a tank of water and diving in a freshwater loch isolated from the sea.

 

[Guba]

Yup, pressure (either atmospheric, in the water column, whereever...) is due to the weight of the material above pressing and squeezing the material below it. That 110 foot silo filled with water will have at its bottom about 4 times the pressure (or about 4 atmospheres) of the air outside the silo wall (about one atmosphere).

 

[DevonDiver]

Yes, the pressure is caused by the weight of the water above the diver. If a diver is submerged below water, then they the weight of that water will exert pressure upon them.

Fresh water weights approx 1kg per litre.
Salt water weights approx 1.03kg per litre.
...so there is a small difference in the pressure exerted at equal depths in salt or fresh water.


For more info on diving physics, take a look at my article: Scuba Diving Physics - The Gas Laws

 

[DBailey]

110 feet underwater is still 110 feet underwater.

 

[fisheater]

Smart-ass answer:

No. Because the top of the silo is at least 110 ft. above sea level (unless it's erected in a depression), if not higher, there will be slightly less total pressure on the diver because the atmospheric pressure will be very slightly less (weather being held constant).


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[Fish in a Barrel]

Smart-ass answer:

No. Because the top of the silo is at least 110 ft. above sea level (unless it's erected in a depression), if not higher, there will be slightly less total pressure on the diver because the atmospheric pressure will be very slightly less (weather being held constant).


Sent from my iPhone using Tapatalk

Aw, dangit! I wanted to be the smart-ass. :depressed:

 

[windapp]

Smart-ass answer:

No. Because the top of the silo is at least 110 ft. above sea level (unless it's erected in a depression), if not higher, there will be slightly less total pressure on the diver because the atmospheric pressure will be very slightly less (weather being held constant).

Of course, 110 ft of air pressure is less than than minute by minute variation in barometric pressure, and significantly less than precision of any depth gauge you are going to use.

 

[Charlie99]

The whole concept of the pressure being solely due to the height difference of the water makes for the interesting thought experiment of what happens when someone goes diving in a sealed container. Imagine that the container is only 5' deep, but that it has a garden hose connection on the bottom of it. Someone connects a 100' garden hose to the tank and then takes the other end up a 100' tall tower. Then he uses another hose to top off the garden hose so it's full.

What depth does the computer of the diver in the tank read ?

As strange as it seems, it will read whatever the vertical distance is between the diver and the top of the garden hose. In other words, around 100', even though the container itself is only 5' tall.

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What's even stranger is that you don't really have to even fill the garden hose. As the diver breathes out, the air goes to the top of the sealed 5' tall container, it will force water up and out of the garden hose. Even if you didn't fill the garden hose once you took it to the top of the 100' tower, eventually the air from the divers would increase the pressure in the container, forcing water up the garden hose until it finally spills out at 100' height.