What does viscosity mean in science

Andrew Zimmerman Jones is a science writer, educator, and researcher. He is the co-author of "String Theory for Dummies. Key Takeaways: Importance of Viscosity Viscosity, the "thickness" of fluid, refers to how resistant a fluid is to movement through it. Water has a low or "thin" viscosity, for example, while honey has a "thick" or high viscosity. The law of viscosity has important uses in such areas as inkjet printing, protein formulations and injections, and even food and beverage manufacturing.

Featured Video. Cite this Article Format. Jones, Andrew Zimmerman. What Is Viscosity in Physics? What Is Buoyant Force?

Origins, Principles, Formulas. Epithelial Tissue: Function and Cell Types. Your Privacy Rights. The gaseous phase is probably the best understood of all the phases of matter. Motor oil is like every other fluid in that its viscosity varies with temperature and pressure. Since the conditions under which most automobiles will be operated can be anticipated, the behavior of motor oil can be specified in advance.

The SAE numbering scheme describes the behavior of motor oils under low and high temperature conditions — conditions that correspond to starting and operating temperatures. The first number, which is always followed by the letter W for winter, describes the low temperature behavior of the oil at start up while the second number describes the high temperature behavior of the oil after the engine has been running for some time. Lower SAE numbers describe oils that are meant to be used under lower temperatures.

Oils with low SAE numbers are generally runnier less viscous than oils with high SAE numbers, which tend to be thicker more viscous. The the mathematical expression describing the flow of fluids in circular tubes was determined by the French physician and physiologist Jean Poiseuille — Since it was also discovered independently by the German hydraulic engineer Gotthilf Hagen — , it should be properly known as the Hagen-Poiseuille equation , but it is usually just called Poiseuille's equation.

I will not derive it here but I probably should someday. For non-turbulent, non-pulsatile fluid flow through a uniform straight pipe, the volume flow rate q m is…. The mathematical expression describing the viscous drag force on a sphere was determined by the 19th century British physicist George Stokes. I will not derive it here but I probably should someday in the future. The formula for the buoyant force on a sphere is accredited to the Ancient Greek engineer Archimedes of Syracuse , but equations weren't invented back then.

Let's combine all these things together for a sphere falling in a fluid. Weight points down, buoyancy points up, drag points up. After a while, the sphere will fall with constant velocity. When it does, all these forces cancel. When a sphere is falling through a fluid it is completely submerged, so there is only one volume to talk about — the volume of a sphere.

Let's work through this. Drop a sphere into a liquid. If you know the size and density of the sphere and the density of the liquid, you can determine the viscosity of the liquid. If you don't know the density of the liquid you can still determine the kinematic viscosity. If you don't know the density of the sphere, but you know its mass and radius, well then you can calculate its density. Newton's equation relates shear stress and velocity gradient by means of a quantity called viscosity.

A newtonian fluid is one in which the viscosity is just a number. A non-newtonian fluid is one in which the viscosity is a function of some mechanical variable like shear stress or time. Non-newtonian fluids that change over time are said to have a memory. Some gels and pastes behave like a fluid when worked or agitated and then settle into a nearly solid state when at rest.

Such materials are examples of shear-thinning fluids. House paint is a shear-thinning fluid and it's a good thing, too. Racing marbles compares the viscosity of common household substances by measuring how fast marbles move through the liquids. Add to collection. Activity idea Racing marbles compares the viscosity of common household substances by measuring how fast marbles move through the liquids.

The PLD webinar Chemistry made simple — properties of matter explores other properties of matter. Go to full glossary Add 0 items to collection. Download 0 items. Scientists say it's the way it This tiny quantum effect influences the way water Now, researchers This work may help improve the flow rate of viscous The results should help scientists study the viscosity in neutron stars, the plasma of the early universe, and other Have We Detected Dark Energy?