# Basic Dimensional Analysis Question

#### armolinasf

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

Porous rock through which groundwater can move is called an aquifer. The volume V of water that, in time t, moves through a cross section of area A of the aquifer is given by:

V/t=KA(H/L)

where H is the vertical drop of the aquifer over the horizontal distance L. The quantity K is the hydraulic conductivity of the aquifer. What are the SI units of K

3. The attempt at a solution

So since this is supposed to be a dimensional analysis question, I figured that I'd start by figuring out what the dimensions of the problem are and I came up with:

[V/t]=[K^a][A^b][(H/L)^c] ===> L^3*t^-1=[K^a][L^2b][L^c-c]

Since there is a time dimension on the left side of the equation I'm guessing that K has a time component but I'm not really too sure how to approach the problem...Thanks for the help

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#### Dick

Homework Helper
Why are you writing [A]=[L^2b]? Area is just plain length squared, right? [A]=L^2. I don't know why you are writing [K^a] either. There's just a K in the formula. And H/L is dimensionless.

#### armolinasf

Alright that clarifies some things for me...so then it would be L^3t^-1=K*L^2 (H/L is dimensionless because L/L is one right?) So for the dimensions to balance out K must be [L/T]? and that would be a speed right?

#### Dick

Homework Helper
Alright that clarifies some things for me...so then it would be L^3t^-1=K*L^2 (H/L is dimensionless because L/L is one right?) So for the dimensions to balance out K must be [L/T]? and that would be a speed right?
Yes.

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