Viscosity and density

[flano]

Are fluids that are more viscous denser. And if an arrow is shot through oil on top of water will it travel faster in the water even though it is denser?

[gen2]

The greater the density of a fluid, the greater the drag, so an object will slow down faster in a denser medium.

[gen2]

Maybe I should have added that viscosity and density are not directly related.  Think of a very viscous liquid like tar or syrup.  If it is heated, there will be a small decrease in density as it expands, but a huge reduction in viscosity.  Incidentally, if my memory of school chemistry is accurate, if you heat sulphur, it first becomes less viscous and then as the temperature rises still further, it becomes very much more viscous again.

[Peter Pedant]

You are a growing lad Flano - Density and viscosity - think of cream ! yum yum

Cream is less dense than milk as it floats

and is clearly more viscous.

Oh in case youre doing a science class, this is called a counter example.....

another counter example - mercury - hg. V dense 13.6 in cgs units and not viscous at all.....

[Hamish]

This is really several questions. There is no direct link between viscosity and dencity between differnt materials. Syrup dencity about 3gcm-3, ver viscous. Mercury dencity 10.5 gcm-3, much less viscous than syrup.

When firing one material through another you also need to take into account the way the two materials interact, this will depend on what you material is made from. Drag is no just down to the dencity, but also the surface chemsitry.

Answer - I dont know.

[howelli]

Some substances have a gel structure due to weak attractive forces which can be disrupted by the application of energy eg. shear force or heating. Some liquids are also dilatent so an arrow shot into it would encounter high resistance to shear but if it was slowly poked through the liquid would be able to enter it more easily. Also glass is a super cool liquid.