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Pressure in a fluid
Beginner
Pressure increases with depth.
P = P₀ + ρghPressure increases linearly with depth: P = P₀ + ρgh. It acts in all directions and depends only on depth, not on container shape.
At 10 m under water: 2 atm total.
Pressure doesn't depend on the container's width.
In more detail
Pressure in a fluid increases with depth, P = P0 + ρgh, where ρ is the fluid density and h is the depth below the surface. It is the same at all points at the same depth.
Real-world uses
- Dams are built thicker at the bottom because the pressure is greater there.
- Divers must consider water pressure, which increases by about one atmosphere every ten metres.
- Divers feel increasing pressure in their ears as they descend, because the pressure of the water rises by about one atmosphere every 10 metres.
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Frequently asked questions
Does shape change the pressure at depth?
No. Pressure depends only on depth and fluid density, not on the container shape.
Why does pressure increase with depth?
Because more fluid lies above, and its weight presses down.
Does the shape of a container change the pressure at a given depth?
No. The pressure depends only on the depth and the fluid density, not on the shape or width of the container.
Related topics in Fluids & Elasticity
Relative density · Pressure · Units of pressure · Pascal's law · Hydraulic press · Atmospheric pressure