Cornstarch Oobleck and Shear Thickening

Easy

What kind of liquid gets harder the faster you hit it? Mix cornstarch and water to create oobleck, a non-Newtonian fluid (a liquid that breaks the usual rules of flow). Unlike most liquids, oobleck thickens under force. Push your hand in slowly and it feels like water. Slap the surface and it turns solid under your palm. This behavior is called shear thickening, the opposite of how real quicksand works. Quicksand gets thinner when disturbed. Oobleck gets firmer. Test both fast and slow movements to feel the difference for yourself.

Hypothesis

The hypothesis is that the hands will sink in quicksand made of cornstarch and water.

Method & Materials

You will mix cornstarch and water to create quicksand, then place your hands on top to see if they sink. Next, you will test if it is easier to move your hand slow or fast, and if it is easier to pull your hand out relaxed or in a fist. Finally, you will punch the quicksand to see if it splatters or stays put.

You will need cornstarch, water, a spoon, and a plastic mixing bowl.

Tinker Crate — science & engineering build kits for ages 9–12 — real tools, real experiments, delivered monthly. (Affiliate link)

See what’s included

Results

In the experiment, they found that hands sank slightly in the quicksand. Moving hands slowly made it easier to move and relaxing the hand made it easier to pull out. When punched, the quicksand stayed put. Quicksand creates a vacuum pressure that makes movement difficult.

Why do this project?

This science project is interesting because it allows you to make your own quicksand and explore how it works. You can learn about the properties of non-Newtonian fluids and how they differ from regular fluids.

Also Consider

To vary the experiment, you could try adding more or less water to the cornstarch mixture to see if it affects how much the hands sink. You could also try using different types of starch, like potato starch or tapioca starch, to see if they create different types of quicksand.