This question is often best answered by example. Imagine a
styrofoam cup with a hole in the bottom. If I then pour honey into the cup I
will find that the cup drains very slowly. That is because honey's viscosity is
large compared to other liquids' viscosities. If I fill the same cup with
water, for example, the cup will drain much more quickly.
Viscosity is a measure of a
fluid's resistance to flow. It describes the internal friction of a moving fluid. A
fluidwith large viscosity resists motion because its molecular makeup gives it
a lot of internal friction. A fluid with low viscosity flows easily because its
molecular makeup results in very little friction when it is in motion.
Gases also have viscosity,
although it is a little harder to notice it in ordinary circumstances.
