Is corn starch non-newtonian? the surprising truth will astound you!

The world of fluids is a fascinating realm where substances exhibit unique behaviors. Among them, non-Newtonian fluids stand out for their unusual flow characteristics. One such substance that has captured the attention of scientists and enthusiasts alike is corn starch. In this comprehensive blog post, we embark on a scientific exploration to determine whether corn starch indeed possesses the enigmatic properties of a non-Newtonian fluid.

What is a Non-Newtonian Fluid?

Non-Newtonian fluids defy the conventional understanding of fluid behavior. Unlike Newtonian fluids, such as water or oil, which flow at a constant viscosity, non-Newtonian fluids exhibit a viscosity that changes with the applied shear force. This means that their resistance to flow is not constant but varies depending on the amount of force applied.

Corn Starch: A Suspect Candidate

Corn starch, a common household ingredient, is composed of tiny starch granules. When mixed with water, these granules form a suspension that exhibits peculiar flow characteristics. Under low shear forces, such as when stirred gently, corn starch behaves like a liquid. However, when subjected to sudden or rapid forces, such as when struck or squeezed, it transforms into a solid-like substance.

Experimental Evidence

To investigate the non-Newtonian nature of corn starch, scientists have conducted numerous experiments. One classic demonstration involves placing a mixture of corn starch and water on a speaker cone and playing a loud sound. The mixture instantly solidifies, forming a “dancing” surface that responds to the vibrations.

Another experiment involves creating a corn starch “oobleck” by mixing it with water in specific proportions. When a finger is gently inserted into the oobleck, it sinks slowly, encountering minimal resistance. However, when the finger is pressed down rapidly, the oobleck behaves like a solid, preventing the finger from penetrating.

Shear-Thickening Phenomena

The unusual behavior of corn starch under rapid shear forces is attributed to a phenomenon known as shear thickening. In this process, as the shear rate increases, the starch granules collide more frequently, forming a network of entangled particles. This network acts as a barrier, increasing the resistance to flow and giving the corn starch a solid-like appearance.

Applications of Non-Newtonian Fluids

The unique properties of non-Newtonian fluids, including corn starch, have led to their application in various fields. Some examples include:

• Body armor: Non-Newtonian fluids are used in body armor to absorb and dissipate impact energy, reducing the risk of injury.
• Shock absorbers: Non-Newtonian fluids are employed in shock absorbers to dampen vibrations and protect delicate equipment.
• Construction: Non-Newtonian fluids are used as additives in concrete to enhance its strength and durability.
• Food industry: Non-Newtonian fluids are used in food products to create textures such as the oozing of ketchup or the viscosity of honey.

Beyond Corn Starch: Other Non-Newtonian Substances

Corn starch is not the only substance that exhibits non-Newtonian behavior. Other examples include:

• Silly Putty: This popular toy is a non-Newtonian fluid that can be stretched, bounced, or molded.
• Ketchup: The thick consistency of ketchup is due to its non-Newtonian properties, which allow it to flow easily when shaken but remain thick when spread.
• Blood: Blood is a non-Newtonian fluid that exhibits shear thinning behavior, meaning its viscosity decreases with increasing shear rate.

Wrap-Up: The Verdict

Based on the experimental evidence and scientific understanding, it is clear that corn starch possesses the characteristics of a non-Newtonian fluid. Its ability to transition from a liquid to a solid-like state under rapid shear forces demonstrates the shear-thickening behavior that is a hallmark of non-Newtonian fluids. The applications of non-Newtonian fluids, including corn starch, extend across various industries, highlighting their unique and versatile nature.

Frequently Asked Questions

1. Why does corn starch solidify when struck or squeezed?
Corn starch solidifies under rapid shear forces due to shear thickening. The starch granules collide and form an entangled network, increasing the resistance to flow and creating a solid-like appearance.

2. What is the difference between a Newtonian and non-Newtonian fluid?
Newtonian fluids have a constant viscosity, while non-Newtonian fluids exhibit a viscosity that changes with the applied shear force.

3. Can other substances besides corn starch exhibit non-Newtonian behavior?
Yes, many other substances, such as silly putty, ketchup, and blood, also exhibit non-Newtonian properties.