Cornflour slimeballs

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Description

Some substances sometimes just can't make up their mind whether they're a liquid or a solid! See what we mean with this messy experiment
Supported by the GGNZ Programme Team

This weird slime acts like a liquid but behaves like a solid when you hit it. Throw a rock into some water and like most liquids, it'll splash everywhere. But some liquids, like quicksand for instance, act differently depending on how much force you apply to them. They're called non-Newtonian fluids and they have some very unusual properties.

The Science: When you mix cornflour with water, the large cornflour particles remain 'suspended' (float around) in the liquid.
Cornflour slime is thick because the particles are packed very close together, yet they are still able to slip past each other.
When you stir the mixture slowly it acts like a liquid because the suspended particles have time to move past each other.
Yet when you put sudden stress on the mixture, by rolling it for example, the water quickly flows out of the area but the particles do not have enough time to move out of the way.
The cornflour particles temporarily stay packed up where they are, which makes the slime
act like a solid.

Resources

Cornflour, water, a wooden spoon, a bowl.
Egg, optional

Instructions

Step 1

Pour half a box of cornflour into a bowl. Then gradually pour water over and mix until it looks and feels like custard.

Step 2

Run your fingers through the liquid.

Step 3

Now try and punch the mixture with your fist.

Step 4

Explain the water runs away first with pressure.
Try putting a fresh egg into the middle of the cornflour mxture in a zip lock bag and dropping it to see if the egg is protected.

Tags

  • beavers
  • Cornflour
  • experiment
  • Non Newtonian Fluids
  • non-newtonian fluid
  • scientist
  • the great indoors

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