Viscosity is resistance to the motion of fluid layers sliding over one another. Density is a measure of forces of attraction between atoms or molecules of same species. Is there any relation between the two?


1 Answer 1


No, mercury is very dense but pours easily Honey is lighter but is very viscous - (changes with temperature though)

Density and viscosity are two different characteristics of a fluid.

Viscosity has the units Poise for dynamic viscosity and Stokes for kinematic viscosity.

  • $\begingroup$ Stokes & Poise are old metric names from the gram-centimetre-second system, that was used by laboratories. In the SI system, there are no special names for the units for [viscosity] (en.wikipedia.org/wiki/Viscosity) & density. The SI units for viscosity are Pa.s, or (N.s)/m2 or kg/(s.m), while the SI unit for density is kg/m3 $\endgroup$
    – Fred
    Commented Oct 8, 2017 at 23:53
  • $\begingroup$ Says here that it is centipoise (cP) and centistokes (cSt) ...rheosense.com/basics/viscosity-units obviously depends on the source as it varies by country... $\endgroup$
    – Solar Mike
    Commented Oct 9, 2017 at 5:10

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