What Would Newton Say?
Liquified mud flows down a mountainside in Nicaragua. Mud is usually a solid. But under some conditions, mud may turn to a liquid state and flow downhill.
The Back Story
- All fluids (liquids and gases) can flow, but they resist flowing to some degree. Some fluids resist more than others (think honey vs. water). Resistance to flowing is called viscosity.
- Most fluids have more-or-less constant viscosity at a given temperature. Such fluids are called Newtonian fluids. That’s because they behave as first described by Isaac Newton in the 1600s.
- A few fluids are non-Newtonian fluids. These fluids behave very strangely and their viscosity can change. Sometimes they act like liquids. Sometimes they act like solids.
- An example of a non-Newtonian fluid is oobleck, a cornstarch-and-water mixture you may have made in school or at home. It’s fun to play with oobleck because it runs through your fingers like a liquid but acts like a solid if you squeeze it. You can see some oobleck and learn how to make it by watching this video: http://www.scientificamerican.com/article.cfm?id=oobleck-bring-science-home
Can You Apply It?
Learn more about Newtonian and non-Newtonian fluids at the link below. Then answer the questions that follow.
- What is a non-Newtonian fluid?
- Besides oobleck and mud, what are some examples of non-Newtonian fluids?
- What are examples of forces that change the viscosity of non-Newtonian fluids?
- What happens when the stress is removed from a non-Newtonian fluid?
- Why might an earthquake cause a mudflow?
- Why would a non-Newtonian fluid be good for body armor?