Hydrostatic Pressure
What is Hydrostatic Pressure
Hydrostatic pressure is that part of the total pressure caused by a the depth of fluid above the point of pressure measurement.
In an enclosed vessel hydrostatic pressure would be total pressure.
In an exposed vessel (like a swimming pool) atmospheric pressure would be added to hydrostatic pressure to find the total pressure.
Hydrostatic pressure is dependant up the density of the fluid, the depth of the measurement and Gravity.
It is assumed in this explanation that the fluid is incompressible.
Hydrostatic Pressure Derived.
Hydrostatic pressure is just the weight of a volume of fluid acting on the base area of the volume.
As we know weight is a force.
Pressure is a Force per unit Area (P=F/A).
Volume = A * height.
Mass = Volume * Density (m=A * h * ρ).
We can calculate the mass of a volume of the fluid by calculating its volume (size) and multiplying by its density.
If multiply the mass by the acceleration due to gravity we now have the weight (or force) (F=ma) on the mass of fluid.
So now we need to find P. If P is force per unit area and the force = A * h * ρ * g. If we divide this by A the A disappears (A/A = 1).
We are left with P = h * ρ * g for the pressure due to a column of fluid h units high.
P = h * ρ * g
- P
- Pressure [N m-2]
- h
- Height of fluid above the point of measurement [m]
- ρ
- Fluid Density [kg m-3]
- g
- Acceleration due to gravity [m s-2]
Example Content
Web References
Java Applet Demonstrating Hydrostatic Pressure
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