Learn Physics in Your Kitchen

Date:10 May 2022 Author: Juandre Tags:,

Home study projects of complex fluids in anyone’s kitchen, using readily available equipment and substances.

Although the COVID-19 pandemic caused many disruptions across the educational system, it also led to some surprising benefits.

In Physics of Fluids, by AIP Publishing, scientists from the University of Illinois at Urbana-Champaign (UIUC) describe their work with students on an at-home study of complex fluid behavior. The course covers rheology, a type of physics that is used to study the way non-Newtonian liquids or semisolid substances flow.

Newtonian fluids have a constant viscosity, but non-Newtonian fluids can deform when force is applied. Sometimes, they respond with plastic flow. Simple rheometric measurements can be carried out in anyone’s home to measure quantities such as shear thinning, viscoelasticity, and other rheological properties.

“We initially called the project Shelter-in-Place Rheometry due to the acute nature of the COVID-19 pandemic and shelter-in-place rules,” said Randy Ewoldt, the professor involved in developing the course. “But we realized that the idea is more general and have since taken to calling it do-it-yourself rheometry.”

 

The projects assigned to the students had two parts: gathering qualitative visual evidence of rheological properties and taking quantitative measurements. The students checked for four behaviors: shear thinning viscosity, viscoelasticity, shear normal stress difference, and extensional viscosity.

 

Do-it-yourself measurement. A student took a single photo (left) of a carbopol suspension in water scooped with a small spatula. The physics of this flowable gel substance, similar to hair gel, was mathematically modeled to estimate the yield stress. Credit: M. Tanver Hossain and Randy H. Ewoldt

 

Even without access to laboratory rheometers, the students developed creative and unique ways to carry out their measurements. They studied a variety of common substances, including buttercream frosting, toothpaste, yogurt, peanut butter, mayonnaise, egg whites, and many other substances available in their homes.

One student, Ignasius Anugraha, developed a compression squeeze flow analysis to study buttercream frosting. Anugraha placed the frosting between two cardboard discs and subjected it to a force by stacking ramekins filled with water atop the discs.

Even without access to laboratory rheometers, the students developed creative and unique ways to carry out their measurements. They studied a variety of common substances, including buttercream frosting, toothpaste, yogurt, peanut butter, mayonnaise, egg whites, and many other substances available in their homes.

One student, Ignasius Anugraha, developed a compression squeeze flow analysis to study buttercream frosting. Anugraha placed the frosting between two cardboard discs and subjected it to a force by stacking ramekins filled with water atop the discs.

Reference: “Do-it-yourself rheometry” by M. Tanver Hossain and Randy H. Ewoldt, 10 May 2022, Physics of Fluids.

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