Demo Title: Oobleck Experiment
Demo overview:
One of the experiments we demoed at the Wonders of Physics (TWOP) Annual Show was the Oobleck experiment. The purpose of the Oobleck experiment is to introduce the concept of a non-Newtonian fluid. These fluids do not follow Newton’s law of viscosity. What that means is that the viscosity of such liquids changes when the liquid is subject to force. The Oobleck is an excellent example of this type of fluid.
Demo Instructor Notes:
While the exact ratio of components can change depending on how dramatic you want the effect to be, mixing 1-part water with 1.5-part cornstarch is all you need to create the Oobleck. Once made, you’ll notice that if you apply pressure, it becomes a hard, solid-like object. Try punching it or squeezing some in the palm of your hand! But once you reduce that pressure, it acts and flows like any other liquid. Try slowly dipping your hand or letting the Oobleck ooze out your fingers.
For the TWOP Annual Show, we took our demo a step further. We filled a kiddie pool with 50 lbs. of cornstarch and approximately 5 gallons of water to create a pool of Oobleck big enough to jump on. We added a bit of pink food dye as well to give it a more colorful look.
Some things to be cautious about: mixing the water and the cornstarch requires a bit of muscle so make sure you have a few people who can help out. Once made, the Oobleck is fine to touch for the first 24 hours but might develop fungi and spores beyond that point so make sure to wash yourself if you come into contact with it! Lastly, it starts to smell so best to dispose of it after 2 days.
Once that’s out of the way, the real joy comes from using our pool of Oobleck! We jumped on top of it and tap danced to show how it really is acting like a solid surface. But then we decided to just stand still and noted the Oobleck slowly swallowing us up like quicksand, which is another non-Newtonian fluid!
