How can we determine viscosity from a graph using Poiseuille's equation?

[jsmith613]

if we use Poiseuille's equation, plotting the varying height of a water tank againts the rate of flow, does the gradient of the graph tell us the viscosity, or do we re-arrange the equation to find viscoisty.

Thanks

 

[jsmith613]

if we use Poiseuille's equation, plotting the varying height of a water tank againts the rate of flow, does the gradient of the graph tell us the viscosity, or do we re-arrange the equation to find viscoisty.

Thanks

Gradient = (πρr^4)/8ηl

Re-arranging this gives: η= (πρr^4)/(8l ∗gradient)
BUT if y = mx + c
y = η
and x = (πρr^4)

So how do we use Poiseullie's equation to find viscosity, when we plot height of tank against (x axis) rate of flow (y)

thanks