# Water velocity

1. Jun 18, 2006

### Idea04

with static pressure(water in a tube or column) not moving. Is there an equation I can use to determine the velocity of the water by the pressure of the water in the tube or column.

2. Jun 18, 2006

### Staff: Mentor

In the first part, you write "static pressure(water in a tube or column) not moving." Then you ask about determining velocity. This is confusing.

There is a pressure head, based on the elevation of the water. There is pressure based on the energy within the water, if the water is confined in a pipe, and there is the differential pressure applied to make the water flow in opposition to friction forces.

Bernoulli's equation would be appropriate. But one has to know more than just static pressure.

One can find useful information here -
http://www.engineersedge.com/fluid_flow/fluid_flow_table_content.htm

Also - Poiseuille's Law -
http://hyperphysics.phy-astr.gsu.edu/hbase/poicon.html

More on Bernoulli's Equation
http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html#beq
http://hyperphysics.phy-astr.gsu.edu/hbase/bercon.html

and
http://wright.nasa.gov/airplane/bern.html

Last edited: Jun 18, 2006
3. Jun 18, 2006

### Idea04

Sorry I didn't explain properly. What I meant was water in a tube that is vertical. The water flows by gravity into another tube. I know how to calculate the pressure of the fluid, But I do not know how to calculate the flow rate of the water using the pressure value of the water in the tube.