Watch: You Can Run Across A Liquid, Thanks to Non-Newtonian Fluids
In this video, people use all kinds of ways to travel across “oobleck,” a non-Newtonian fluid that has the properties of both a liquid and a solid. In short, if you apply sudden force (like stomping on it or running across it) it behaves like a solid. However, if you slowly apply force (like gently stepping on it or slowly scooping some with a spoon) it will behave like a liquid.
You can make your own solution of oobleck using 1 part of water to 1.5–2 parts of corn starch (it is nontoxic).
In the first video, watch as individuals dance, jog, jig, and attempt to run across the substance while applying force quickly enough so that they don’t sink.
See the people make their attempts:
The above video comes from Kuala Lumpur, Malaysia. Hong Leong Bank obtained 8,000 liters (2,100 gallons) of non-Newtonian fluid for the stunt.
In the below video, oobleck is punched over and over, and a slow-motion camera is used so that you can easily see how the substance behaves.
Watch the punching here:
So, how does all of this work?
In essence, fluids resist flow (this is something that is known as “viscosity”). In order to understand how this operates, try and picture a flowing liquid as a series of layers. Each of these layers of liquid are moving about and sliding past each other. The fluids resistance to flow exists as a result of the friction between these various layers in the water.
Newton devised a simply way to explain this phenomenon. In short, the slower that one layer of a fluid slides over another, the less resistance there is.
Fluids (like water) that behave according to Newton’s model are called “Newtonian fluids.” Doubling the speed at which these layers flow past each other doubles the resisting force. In non-Newtonian fluids, doubling the speed does not double the resistance. Rather, viscosity is variable based on applied stress.