Have you ever heard of Oobleck? I first discovered this substance, a mixture of water and cornstarch, while doing a science experiment in elementary school. Oobleck defies the laws of nature, or at least Newton’s laws. Though it initially appears like a liquid, when you apply pressure, it turns into a solid. How can a substance be both simultaneously?
The reason is because Oobleck is classified as a non-Newtonian fluid, meaning that it does not follow Newton’s law of viscosity. Viscosity is a property that describes how a fluid flows, or more simply, how thick or thin it is. When a fluid’s viscosity is constant, it is called a Newtonian fluid. Most fluids fall under this category. However, Oobleck is one of the few exceptions. Its viscosity is depended on the amount of force applied to it. Known as a shear thickening fluid, it appears thicker as you physically manipulate it. This behavior is explained by the structure of cornstarch, the main ingredient in Oobleck. Cornstarch particles are long and thin, when you mix it with water, the faster you move it, the more tangled the particles become, thus “hardening” and imitating the solid state. The increased amount of friction created through motion also causes increased resistance of the mixture to flow. It is important to note that Oobleck is a suspension, not a solution. This means that the cornstarch does not dissolve in water. Instead, it is suspended in the liquid. If you let it sit in a glass for a while, the cornstarch will separate from the water and settle at the bottom.
Aside from being a fun science experiments for students to enjoy, Oobleck has other potential uses. There have been cases of several patents for the industrial use of the material. One proposed usage was for a system to fill potholes. Permanently fixing potholes involves economic and seasonal considerations. One alternative was to use bags of Oobleck. When the bag is placed in the hole, the Oobleck acts as a liquid to fill the space. When a car drives over it, it hardens, preventing damage to the vehicle.
Check out this video by Todd Scott to see the concept in action!
Another use was for a gear damper. Gear dampers are used in cars to control the movement speed of trays and glove boxes. Oobleck could be used to ensure that these components open when used normally but remain closed when a great force is applied, like in a car accident.
Experimenting with Oobleck is a great way to explore the properties of non-Newtonian fluids. Though they are typically not mentioned in your typical science class, they exists in our everyday lives. Some common examples include Ketchup, paint, and toothpaste. Though, unlike Oobleck, these fluids become thinner when agitated. They are known as shear thinning fluids. In addition to serving as a fun science experiments, substances like Oobleck can also have practical real world applications!
Sources
Lima, E. (2020). Studying the Oobleck with video-analysis. IOPscience. https://iopscience.iop.org/
Oobleck. Imagination Station.
https://www.imaginationstationtoledo.org/education/diyactivities/Oobleck#:~:text=Oobleck%20is%20a%20suspension%20of,until%20you%20release%20the%20pressure.
Oozing oobleck activity – science museum group learning. Science Museum Group. (2022, August 15). https://learning.sciencemuseumgroup.org.uk/resources/oozing-oobleck/
Ralphs, A.(2023, August 4). Oobleck recipe. One Hundred Toys. https://www.onehundredtoys.com/oobleck-recipe/
The IP Bloggers. (2018, February 20). Surprising uses for Oobleck. Industrial IP. https://www.industrialsip.com/2018/02/surprising-uses-for-Oobleck.html#:~:text=When%20the%20bag%20is%20placed,necessary%2C%20and%20is%20environmentally%20benign.