Understanding Submarine Pressure: Importance and Calculations"

In summary: English, I just wanted to know if the atmospheric pressure inside the submarine has a different direction and if it has a different direction, why do we neglect it in the equation for total pressure on the submarine. In summary, the pressure inside a submarine under water is calculated by adding the water pressure (determined by the depth and density of the water) to the atmospheric pressure inside the submarine. However, since the atmospheric pressure inside the submarine is usually kept at the same level as the surface air pressure, it is negligible in the overall pressure calculation. Therefore, the total pressure on the submarine is primarily determined by the water pressure.
  • #1
Misr
385
0
The pressure in a submarine inside water
P=h*ρ*g+Pa
Okay,
Since there's Atmospheric pressure inside the submarine (Pa),we calculate the total pressure on the submarine from the relation=h*density*g
we just neglect the atmospheric pressure
why?I don't understand?
Why don't we calculate the total pressure from the relation P=hρg+2Pa?
does the atmospheric pressure in the submarine have a different direction?
 
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  • #2
Where did you get those equations? For a rigid hull sub, the pressure inside can be whatever the designer and operator choose. You can't calculate it.
 
  • #3
Misr said:
The pressure in a submarine inside water
P=h*ρ*g+Pa
Okay,
Since there's Atmospheric pressure inside the submarine (Pa),we calculate the total pressure on the submarine from the relation=h*density*g
we just neglect the atmospheric pressure
why?I don't understand?
Why don't we calculate the total pressure from the relation P=hρg+2Pa?
does the atmospheric pressure in the submarine have a different direction?

Why not ?
Do you know how less in the atmospheric pressure as in comparison to water exerting pressure on submarine below water ? Moreover atmospheric pressure is exerted maximum on surface of water. Do you know how below is the submarine from surface level ?

Counter question having same logic : Why do you think air friction is neglected during free fall of body ?

Pressure inside is independent of outside , yes Halls.
These are opposite too. You just can't add them Misr.
:)

@ HallsofIvy and Russ Watters
[I thought he was only referring to atmospheric pressure on surface of water.]
 
Last edited:
  • #4
Even "general physics" questions have to make sense. A submarine is made of rigid metal. The pressure on the outside (as long as it is not great enough to fracture the metal) is completely independent of the pressure on the inside.
 
  • #5
The formula (which would be clearer if all symbols were defined) appears to be that on the outside of the submarine. Since almost all the outside pressure is from the water, neglecting the air pressure doesn't make much difference. Also the air pressure on the inside may be kept (for comfort) at roughly that of the surface air pressure, so the pressure formula would give the net pressure on the hull.
 
  • #6
Pressure outside the submarine hull = h*ρ*g+Pa
Pressure inside the submarine hull = Pa

Pressure differential on the hull = outside pressure - inside pressure = h*ρ*g + Pa - Pa = h*ρ*g
 
  • #7
Resolved
Thanks very much
 

FAQ: Understanding Submarine Pressure: Importance and Calculations"

What is submarine pressure?

Submarine pressure refers to the force exerted on a submarine by the surrounding water. This pressure increases as the submarine dives deeper into the ocean.

Why is understanding submarine pressure important?

Understanding submarine pressure is crucial for the safety and operation of submarines. It helps engineers design and build submarines that can withstand the pressure of deep waters, and it allows submarine operators to calculate the maximum depth they can safely dive to.

How is submarine pressure calculated?

Submarine pressure is calculated using the formula P = ρgh, where P is pressure, ρ is the density of water, g is the acceleration due to gravity, and h is the depth of the submarine. This formula takes into account the weight of the water above the submarine and the force of gravity acting on it.

What factors affect submarine pressure?

The main factors that affect submarine pressure are depth, density of water, and gravity. The deeper the submarine dives, the higher the pressure will be. The density of water also increases with depth, which further contributes to the pressure. Additionally, the force of gravity varies slightly in different locations, so the pressure may also be affected by the submarine's location.

How does submarine pressure impact the human body?

Submarine pressure can have a significant impact on the human body. As the pressure increases, so does the pressure on the body, particularly the lungs and ears. This can lead to discomfort, pain, and even injury if the pressure is not properly managed. Therefore, it is important for submariners to understand and monitor the pressure within the submarine to ensure their safety and well-being.

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