Flow of water vs mercury vs treacle

[vorcil]

Imagine a hollow cylinder filled with water (a water tank)
a hole is near the bottom of the cylinder

the hole is covered, the tank filled with water and then the hole is uncovered

the volume flow rate = Q
h = the height of the hole from the water level

Q = Pi*r^2 * (squareroot 2gh)
(i solved this from)

q=av (area * velocity)

area of cylinder = pi R^2

velocity as it leave the hole = Squareroot (2gh) -> (h being the height from the hole to the water level)


after doing the experiment and graphs and stuff i got the velocity of the water jet to be 2.816 ms^-1

question:
would the velocity be different if i had mercury in the cylinder instead of water?

i know the velocity is determined by $$\sqrt{}(2gh)$$
so the density and mass of the liquid shouldn't make a difference!

but that made me think, what if i put something like honey or treacle into the cylinder.
it would definitely be slower, So wouldn't $$\sqrt{}(2gh)$$ be wrong? even though my textbook says to use that formula?

 

[LowlyPion]

Why stop at treacle? Consider pitch.

http://en.wikipedia.org/wiki/Pitch_drop_experiment

You can imagine that where viscosity gets to be 230 billion times that of water, your classical equations might need modification.

 

[Dweirdo]

this might help:
http://hyperphysics.phy-astr.gsu.edu/hbase/press.html#fpe
http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html#beq