Viscosity is a liquid’s resistance to flow
– if a liquid has a high resistance to flow, it’s said to be a viscose liquid.
You can test out the viscosities of liquids
around your house – first find 3 or 4 different types of liquids – such as
tomato sauce, honey, oil, milk, water, shampoo or toothpaste.
You’ll also need a baking tray, something
to prop it up with, and some newspaper.
Find an area outside where you can do this
experiment because things might get messy.Prop your baking tray up on something so it’s on a fairly steep angle
between 45 and 90 degrees. Lay some newspaper out at the bottom.
Next, put a large drop of each of your
liquids at the top of the baking tray.Watch
how quickly each of the liquids flow downhill to the bottom of the baking
The liquids that reach the bottom the
fastest are the liquids with the lowest viscosity.The liquids that take longer to reach the
bottom have a higher viscosity.
You’ll find that a liquid like water has a
really low viscosity and will reach the bottom of the baking tray really
quickly, whereas a liquid like toothpaste has a very high viscosity and will
take a very long time to reach the bottom of the baking tray.
The reason liquids have different
viscosities is mainly because of the shape of the molecules (or tiny bits) that
make up the liquid.Non-viscous liquids
are made of simple molecules that flow easily past each other, but the
molecules of more viscous liquids are more complicated, so they tend to catch on
each other and don’t flow as easily.