# Capillary Tube Problem

1. May 12, 2014

### maxnormal

1. The problem statement, all variables and given/known data

A drip-irrigation emitter constructed of a coiled capillary tube is inserted into the wall of a drip irrigation line with a constant water pressure of 5 psi. Compute the required length of the emitter’s capillary tube to produce an emitter dripping rate of 2 litres per hour if the capillary tube diameter is 1mm.

2. Relevant equations

Pressure = Force * Area
Volume of Cylinder = ∏ * Length *Radius^2

3. The attempt at a solution

I converted all the units into SI. I know I need to solve for length of the cylinder, but when I try to equal the cylinder dimensions to 5psi nothing works out. Just don't know how to approach the problem yet. Any help would be appreciated. Thanks.

5 pounds/inch^2 = 34,473.7865 kg/ms^2
2Litres/hour = 5.55x10^-7 m^3/s
diameter = 1mm = 0.001m

2. May 12, 2014

### Staff: Mentor

Hi Maxnormal. Welcome to Physics Forums!!!!

Are you learning fluid mechanics? Have you learned about the Hagen -Poiseuille viscous flow equation?

Chet

3. May 12, 2014

### maxnormal

Hey! Right now I am learning Soil Physics. And I have not learned of that equation yet. Will I need that equation to solve the problem?

4. May 12, 2014