non-newtonian fluid
Definition
In physics, a non-Newtonian fluid is a fluid whose viscosity, or thickness, changes with the force applied to it. This means that the fluid can behave like a solid or a liquid depending on how it is being used.
Some common examples of non-Newtonian fluids include:
- Oobleck: Oobleck is a non-Newtonian fluid that is made from cornstarch and water. It is thick and gooey when you stir it slowly, but it becomes hard and rubbery when you hit it hard. This is because the cornstarch molecules are arranged in a way that allows them to slide past each other easily when there is a small amount of force applied, but they lock together when there is a large amount of force applied.
- Slime: Slime is another non-Newtonian fluid that is made from glue, water, and borax. It is stretchy and gooey when you play with it, but it becomes hard and rubbery when you hit it hard. This is because the borax molecules act as cross-linkers, which means that they connect the glue molecules together. This makes the slime more resistant to deformation when it is hit hard.
- Toothpaste: Toothpaste is a non-Newtonian fluid that is made from water, soap, and abrasives. It is thick and creamy when you squeeze it out of the tube, but it becomes thin and runny when you brush your teeth. This is because the soap molecules act as surfactants, which means that they reduce the surface tension of the water. This makes the toothpaste easier to spread and less likely to stick to your teeth.
Non-Newtonian fluids have many different applications. They are used in products like toothpaste, cosmetics, and lubricants. They are also used in industrial applications like oil drilling and mining.
How can the word be used?
Non-Newtonian fluids are used in a variety of applications, including paints, cosmetics, and food products.
Different forms of the word
Noun: A fluid whose viscosity is not constant, but depends on the applied shear stress.
Adjective: Relating to non-Newtonian fluids.
Etymology
The word "non-Newtonian" is made up of the prefix "non-," which means "not," and the name of Isaac Newton, the English physicist who developed the laws of motion. Newton's laws of motion describe how objects move under the influence of forces.
The word "non-Newtonian fluid" was first used in the early 20th century. It was used to describe fluids that did not follow Newton's laws of motion.
Question
What is a non-newtonian fluid?
AQA Science Exam Question and Answer
Question:
What is a non-Newtonian fluid, and how does its behaviour differ from that of a Newtonian fluid? Provide an example of a non-Newtonian fluid and explain how its properties change under different conditions.
Answer:
A non-Newtonian fluid is a type of fluid whose viscosity (resistance to flow) changes in response to the applied stress or shear rate. Unlike Newtonian fluids, which maintain a constant viscosity regardless of shear stress, non-Newtonian fluids exhibit variable viscosity under different conditions.
An example of a non-Newtonian fluid is cornstarch mixed with water, creating a substance commonly known as "oobleck." When handled gently, oobleck flows like a liquid, but it becomes thicker and more resistant to flow when force is applied, such as squeezing it. This behaviour is due to the interactions between water molecules and starch particles. When subjected to stress, the starch particles become more tightly packed, leading to an increase in viscosity and a solid-like behaviour.
In contrast, Newtonian fluids, like water and most oils, maintain a constant viscosity regardless of the force applied. Their flow behaviour is predictable and follows Newton's law of viscosity, where the rate of deformation is directly proportional to the applied shear stress.
Understanding non-Newtonian fluids is crucial in various industries, from food processing to engineering, where the ability to manipulate a fluid's viscosity can lead to innovative applications.