Wednesday, August 16, 2017

Science this week

Understanding Viscosity

This week we learnt about viscosity.

It is commonly perceived as "thickness", or resistance to pouring. Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. Thus, water is "thin", having a low viscosity, while vegetable oil is "thick" having a high viscosity.

We completed two experiments to learn about viscosity:

The first one we look at was race the liquids. We predicted which liquid would be the fastest:
Paint, Dish washing liquid or water.

The paint had the highest viscosity so it didn't move very far at all.

Next, we looked at oil and golden syrup in a bottle:

We then flipped the two bottles at the same time and found that the syrup has the highest viscosity. The results were slightly changed because Miss Prentice left the bottles on the window in the hot sun and the syrup has melted so it moved quicker than it normally would.

Newtonian and Non-Newtonian fluids:
We also learned this week that the concept of viscosity came from Isaac Newton and that fluids that behave in a certain way are called Newtonian fluids, and fluids that don't follow the rules of viscosity are called non-Newtonian fluids. So we made cornflour slime to experiment with non-Newtonian fluids. Did you know that Dr. Suess called this Oobleck.

To make cornflour slime you need:
200 grams of corn flour, 200 ml of water and food colouring (optional).

Mix well and see what happens!

When you hit your slime hard it acts like a solid when you push slowly your hand will sink.

Watch this clip from Myth busters about walking on water:

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