…erroneously describe glasses as undercooled viscous liquids, but this is actually incorrect. Along the section of route 2 labeled liquid in Figure 3, it is the portion lying between T_f and T_g that is correctly associated with the description of the material as an undercooled liquid (undercooled meaning that its…

…and are further distinguished as Newtonian fluids if the viscosity is constant for different rates of shear and does not change with time. The viscosity of non-Newtonian fluids either varies with the rate of shear or varies with time, even though the rate of shear is constant. Fluids in a…

Viscous liquids consist of molecules that, like those of the perfect fluid, are in contact with one another but do exert forces on one another so that shearing motions within the liquid are resisted. These internal shearing forces produce the characteristic behaviour of liquids such…

…for what is called a Newtonian fluid is

…in this way are called Newtonian fluids in honour of Sir Isaac Newton, who first formulated this mathematical description of viscosity.