Definition of Viscosity
In everyday life the term viscosity has a certain meaning, but acquires a very different one if we refer to its scientific explanation. Thus, when touching certain sticky and dense substances, we say that they are viscous. This is what happens with honey, some dairy products, mustard, certain sauces or some cosmetic products. From scientific criteria, viscosity is a law that was defined by Isaac Newton.
From a scientific point of view
Some fluid substances have a certain degree of internal friction and this phenomenon is known as viscosity. It is a frictional force between adjacent layers of the fluids. In other words, viscosity is a resistance in the form of internal friction. In liquids the viscosity is mainly due to the electrical forces of cohesion of the molecules that make up matter. In gases , this phenomenon occurs due to collisions between the molecules. From a scientific point of view the study of viscosity must be placed in the area of fluid mechanics.
Newton's law of viscosity
Viscosity is the friction between the different layers of a fluid. If a given force is applied to each plate, this generates an effort on the fluid. Thus, a fluid is viscous when its mechanical energy is not kept constant and the fluid is non-viscous when it is kept constant. This idea was explained by Newton through a law that bears his name. Said law states that in a fluid the friction tension applied in one direction is proportional to its speed and that said situation is measurable with a viscosity coefficient.
A fluid is a substance that continuously deforms under the action of forces and can be a gas or a liquid. If we think of a pipe with a certain fluid inside, there are a number of aspects that determine the behavior of a fluid:
1) the pressure change,
2) the height at which the pipe is located (the deeper, the more pressure),
4) flow rate.
The viscosity of the oil in the engines
All liquids have a viscosity grade and with respect to oils some have more viscosity than others. For an engine of a machine to work properly it is necessary that the oil used has a correct adhesion to the metal . It must be thought that the oil protects the moving parts of an engine and, therefore, its viscosity has to adapt to the temperature changes that affect each engine.
Photos: Fotolia - fortsite / trompinex