Q: Solve Poiseuille's Law for Volume Flow Rate

[Nathan phisi]

Homework Statement

A large tank contains oil with a viscosity of η = 7.5 Pa s. The tank has walls and floor which are 2 cm thick, but there is a small circular hole at the base of the tank through which oil is leaking. The fluid pressure at the base of the tank is 126 kPa (atmospheric pressure is 101 kPa) and the radius of the hole is 1.5 mm. What is the volume flow rate at which the oil is leaking out of the tank (in m3 s −1 )?

(A) 1.2 × 10−3 (B) 7.1 × 10−4 (C) 2.7 × 10−5 (D) 4.1 × 10−6 (E) 3.3 × 10−7

Homework Equations

Poiseulle law equation (maybe)

The Attempt at a Solution

I'm pretty sure this has to do with Poiseulle's law, because of the variables. I have all variables for the P law equation (given in the equation) except length (and the needed flowrate). I do have trouble with 2 variables being unknown, so a little help with that would be greatly appreciated :)

 

[Chestermiller]

You do know the length.

 

[Nathan phisi]

Oh dang, you're right, the length was 0.02m. Don't ask me how long I was on this question and didn't click. Thanks!