Viscosity facts for kids

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This picture shows how thick liquids flow. The purple liquid at the bottom is thicker than the clear one above.

Viscosity is a cool science word that describes how much a fluid (like a liquid or gas) resists flowing. Think of it as how "thick" or "thin" a liquid is. For example, water has a low viscosity because it's very "thin" and flows easily. On the other hand, syrup or tar have a high viscosity because they are "thick" and flow much more slowly.

You can easily test a liquid's viscosity! Just see how fast it runs down a slope. Water would zoom down quickly, but syrup would take a long, slow journey to the bottom.

Types of Viscosity

Scientists measure viscosity in two main ways:

• Dynamic viscosity: This measures a fluid's actual resistance to flow. It's like measuring how much force you need to push something through the liquid. The units for this are pascal seconds.
• Kinematic viscosity: This is about how fast a fluid flows when gravity is pulling it. It's the dynamic viscosity divided by the fluid's density. The units for this are metres per second squared.

Viscosity and Volcanoes

Viscosity is super important for understanding volcanoes! It helps scientists guess when a volcano might erupt and how powerful that eruption could be.

When lava is very thick (high viscosity), it has a hard time flowing out of the volcano. This can cause pressure to build up inside. If the pressure gets too high, the lava might burst out in a very violent eruption!

But if the lava is thin (low viscosity), it flows out easily, much like water. This usually leads to calmer eruptions where the lava just oozes out.

Where the Word Comes From

The word viscous comes from the Latin word viscum. This word means "sticky," which makes a lot of sense when you think about thick, sticky liquids!

Images for kids

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  Viscosity, which is like the steepness of each line, changes for different materials.

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  Common glass viscosity curves.

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  Honey being drizzled, showing its viscosity.

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  This graph shows how the viscosity of B2O3 changes with temperature.

See also

In Spanish: Viscosidad para niños