Oobleck has been around for a long time my favorite example of non-newtonian fluidand i’m not alone.It’s very popular “Kitchen Science” experiment Because it’s simple and easy to make. Mix one part water and two parts cornstarch, add a little food coloring for fun, and you’ve got oobleck. It behaves as a liquid or a solid depending on the degree of stress applied. Stir slowly and thoroughly until it becomes a liquid. The harder you punch, the more solid it becomes under your fist. You can also fill a small pool with materials and walk across it. Because Ooblok freezes every time he goes down. It’s a flashy physics demo that comes up a lot naturally. on youtube.
The physical principles underlying this simple substance are surprisingly subtle and complex, which is why they are of interest to scientists. Molecular engineers at the University of Chicago say they used a dense suspension of piezoelectric nanoparticles to measure what happens at the molecular level as oobleck transitions from liquid to solid behavior. new paper Published in the Proceedings of the National Academy of Sciences.
Towards the end of his life, Isaac Newton described the properties of an “ideal liquid.” One of those properties is viscosity, loosely defined as how much friction/resistance there is to flow through a particular substance. Friction occurs because a flowing liquid is essentially a series of layers sliding against each other. The faster one layer slides over another, the greater the resistance. The slower one layer slides over another, the less resistance there will be. But the world is not an ideal place.
in newton’s ideal fluid, viscosity is highly dependent on temperature and pressure. Water continues to flow regardless of other forces acting on it, such as stirring or mixing. Non-Newtonian fluids straddle the boundary between liquid and solid behavior because their viscosity changes in response to applied strain or shear force. Stirring a glass of water creates a shearing force that shears the water out of the way. Viscosity remains unchanged. However, for non-Newtonian fluids like oobleck, the viscosity changes when a shear force is applied.
For example, ketchup is a shear-thickening non-Newtonian fluid. This is one of the reasons he says ketchup doesn’t come out faster when you tap the bottom of the bottle. When force is applied, the viscosity increases. Examples include yogurt, gravy, mud, pudding, and rich pie fillings. And so is Oobrock. (The name comes from his 1949 Dr. Seuss children’s book. Bartholomew and Oobleck.) In contrast, non-drip paint exhibits a “shear-thinning” effect, making it easier to apply with a brush, but becoming more viscous once it gets on the wall.
In 2019, Developed by MIT researchers This is a useful mathematical model for predicting how oolock changes from liquid to solid and back again under different conditions. They adapted their working model to a granular material: wet sand. Although there are some similarities, Oobleck’s cornstarch particles are 100 times smaller than grains of sand (1 to 10 microns). At these small size scales, the physics are markedly different. For example, temperature has a large effect on cornstarch particles, as does the charge that builds up between the particles and causes a repulsive effect. Therefore, while wet sand has the same viscosity at a given packing density regardless of applied stress (such as stirring or punching), the viscosity of oobleck changes dramatically.
MIT team specifically added They add a “cohesiveness variable” to their model to describe the amount of frictional contact between cornstarch particles, rather than lubricated contact, and predict how that new variable changes in response to different stresses. The researchers then tested the model’s predictions by using previous experiments, which involved shoving and shearing Oobleck between two plates and firing a simulated small projectile into Oobleck’s tank. A computer simulation of the laboratory experiment was performed. These simulations were consistent with experimental results from previous studies.