# Physics and Irrigation

1. Apr 18, 2009

### Cerumen

I'm working on a drip irrigation project to present to the management at my work (a home improvement store) in hopes that my design will become a display in the store. However, even with my current knowledge of physics, I can't seem to figure out the following issue:

I'm using a 50 gallon rain barrel to collect rain water to power the irrigation system. Those not familiar with drip irrigation, it is simply a hose capped at one end with "drip locations" along its entire length, powered by some water source. The exit point for water to leave the barrel is located roughly 1.5 inches from the base of the barrel and has a diameter of 1/2 inch.

** If the rain barrel is completely full, sitting at ground level and a 10 foot x 1/2 inch irrigation hose is used (hose not perforated at this point), what pressure is exerted on the cap of the hose, ie the very end if stretched out in a line?

** Again, if the rain barrel maintains the same conditions (filled with water, hose dimensions and straight line) but is raised off the ground by, say 12 inches, what is the new pressure exerted on the cap of the hose? By what factor does this value increase as the barrel is elevated in 12 inch increments?

** How is the pressure effected across the length of the hose if 3mm perforations are made every 6 inches? Obviously, it will decrease, but by what extent?

** By what extent is this scenario changed with less water in the barrel? 1/2 full? 1/3 full?

There are more factors at play here than what I have outlined with these questions. However, with solid data on these inquiries, I can begin to calculate the other variables.
This design is clearly intended to work without the use of an electric pump.

Thank you in advance for any information in regard to this topic.

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