Viscosity is an important factor in determining the forces that must overcome when liquids are used for lubrication and transported in pipes. ATTENTION: the reciprocal of viscosity is called fluidity, a measure of smoothness. There are many methods one can use to measure the viscosity of a fluid, the easiest and most straightforward being to drop a sphere of a certain diameter into a transparent container containing the fluid whose viscosity one is trying to determine. Molasses, for example, has a higher viscosity than water because it is more resistant to flow. If we immerse a foreign body in the fluid under consideration, it will encounter a resistance whose strength varies depending on the fluid’s degree of viscosity. Viscosity in physics is one of the properties of matter whereby the motion of molecules with respect to surrounding molecules encounters, due to intermolecular forces, a resistant force: in solids it is highest, but lowest in liquids and gases.