Making Non-Newtonian Fluid!

Materials:

• A bowl

• 4 tablespoons of cornstarch (1/4 cup)

• 4 tablespoons of water (1/4 cup)

Steps:

1. Add 4 tablespoons of cornstarch into a bowl. Then, add 2 tablespoons of water and slowly stir until all cornstarch is wet.

2. Slowly add the rest of the water and continue slowly stirring it.

3. Slightly tap your finger on the mixture. If it appears hard when you tap it and also appears to be a liquid when you stir it, then you made a non-Newtonian fluid!

Advice: if your mixture is too watery, you can add more cornstarch.

Explanation:

In order to understand a non-Newtonian fluid, we need to first understand viscosity. Viscosity is a measure of resistance that a liquid has. In other words, imagine honey and water. Honey has a high viscosity because it does not flow easily. Water has a low viscosity because it flows very easily.

In a non-Newtonian fluid, viscosity changes based on the pressure applied to it. It gets thick and hard like a solid when you apply pressure, and it gets flowy like a liquid when you are slow and apply no pressure at all.

Why does this happen? Believe it or not, scientists are still not sure why, although there are some theories. One theory suggests that the applied pressure forces the particles of the non-Newtonian fluid to pack into groups and contract, which results in the thickening of the fluid. Another theory suggests when the pressure is applied slowly, then the chains of polymers have time to rearrange themselves in a liquid, so they stay a liquid. When the pressure is applied quickly, then the polymer chains do not have time to rearrange themselves, so they resist the pressure and thicken.

Photo Credit: Rory MacLand[CC By 2.0], via Flickr