Water Pressure and Internal (Air) Pressure

• ipen
In summary, the net force on a tube with different internal pressures submerged to the same depth is proportional to the pressure difference. This force is derived from the water and air pressure combo, with the tube itself playing a role in supporting the pressure difference. Other forces, such as buoyant forces, may also be present but are likely less significant.
ipen
If you have, say, two tubes of different internal pressures submerged to a given depth (for sake of the example, let's just say 1,000M underwater or 100 ATM), will the smaller internal air pressure tube experience a greater relative force from the water pressure? The water pressure on both tubes should be the same from the outside, but is there an additional effect where water tries to equalize the pressure at a greater magnitude of force on the tube with less internal air pressure? I guess an extreme, clearer hypothetical comparison would be between a tube with a vacuum on the inside compared with a tube with air pressure equal to 99.99% of the water pressure on the inside. I'm also assuming that the tube's microstructure is impermeable to water, and that the tube is strong enough to withstand the water pressure at the given depth.

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ipen said:
is there an additional effect where water tries to equalize the pressure at a greater magnitude of force on the tube with less internal air pressure?

Yes. The net force is proportional to the pressure difference.

If the tube distorts in any way that changes the volume then the pressure inside can change meaning the pressure differential and the net force will also change.

Is this force derived from the water and air pressure combo, or something else?

What else could it be?

The pressure on the outside surface of the tube is the water pressure. If the tube is flexible, the pressure on the inside surface is also the water pressure.

The tension or compression stress in the circumferential direction (i.e., the so called hoop stress) supports the difference in pressure between the inside and the outside of the tube. So the tube itself is part of what is happening.

Chet

I was wondering if there were other forces, maybe even buoyant forces that would be significant.

But from what I can tell, it seems like the major ones are water and air pressure.

What is water pressure?

Water pressure is the force exerted by water on the walls of a container or on any object it comes into contact with. It is measured in units of force per unit area, such as pounds per square inch (psi) or Newtons per square meter (N/m^2).

How is water pressure affected by depth?

Water pressure increases with depth due to the weight of the water above. The deeper you go, the greater the weight of water pushing down and the higher the water pressure. This is known as hydrostatic pressure.

What is internal (air) pressure?

Internal pressure is the air pressure inside a container or an object. It is measured in the same units as water pressure, such as psi or N/m^2. In the case of a closed container, the pressure of the air inside is equal to the pressure of the water outside.

How does water pressure affect objects?

Water pressure can affect objects in different ways. For example, if an object is submerged in water, it will experience an upward buoyant force due to the pressure of the water pushing up. On the other hand, if an object is on the surface of the water, it will experience a downward force due to the weight of the water above.

How do changes in temperature affect water pressure?

Changes in temperature can affect water pressure in two main ways. First, as temperature increases, the volume of water expands, leading to an increase in pressure. Second, changes in temperature can also affect the density of water, which in turn affects the pressure it exerts at a given depth.

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