Thixotropic fluids show the opposite behaviour to rheopectic fluids — they get runnier as a sustained force is applied. Another kitchen based example is honey. However, if you give it good stir then it returns to the right consistency to put on your toast.
This graph shows how both rheopectic and thixotropic non-Newtonian fluids behave as a force is applied. The key thing here is that the force has to be sustained — the longer the force is applied the more the viscosity changes. Unlike rheopectic and thixotropic non-Newtonian fluids, those described as dilatant will change their viscosity dependent on how much force applied is, not how long for.
The harder you hit a dilatant fluid the more viscous it becomes. One such example is Oobleck — a fluid similar to raw custard make of corn starch mixed with water. Unstressed it behaves as you would expect, but applying a strong force makes it more viscous and it behaves much more like a solid — a fact that allows you to walk on it. In the video at the bottom of this page you will see someone walking across Oobleck. It has been slowed down to frames per second.
Walking quickly and stamping down hard on the fluid causes it to become more viscous and support your weight. Pseudoplastics are the opposite of dilatant fluids — they get runnier the harder the force applied. Returning to the kitchen you use the fact that tomato ketchup is a pseudoplastic whenever you try and get any out of the bottle and onto your chips. Continue mixing until your mixture reaches the consistency of honey. You may find you need to add more cornstarch or water.
You can scale this recipe up or down, but try to keep the ratio one part water to two parts cornstarch. You can add food coloring, if desired. I hope you take the time to explore non-Newtonian fluids by making oobleck. People of all ages are amazed by its properties! Non-Newtonian Fluids. Physicists foil classic oobleck science trick by Science News for Students.
No-Hit Wonder! Glad you enjoyed it!! Now that the weather is warmer, I plan to make an even bigger batch of Oobleck in my kiddie pool! Your email address will not be published.
Save my name, email, and website in this browser for the next time I comment. Notify me of follow-up comments by email. Notify me of new posts by email. Skip to content. Atoms are arranged differently in solids, liquids, and gases. An explanation of the properties of a shear-thickening fluid under pressure. Rohrig, Brian. An explanation of the properties of a shear-thinning fluid under pressure. Share this: Click to share on Pinterest Opens in new window Click to share on Facebook Opens in new window Click to share on Twitter Opens in new window Click to email this to a friend Opens in new window Click to print Opens in new window.
Leave a Comment Cancel Reply Your email address will not be published. Hi, I'm Kristin! I share tools and resources to help you understand and teach science.
Sign up to receive my newsletter and exclusive freebies. Sign me up! Get My Freebie! Thanks for subscribing! One last step to access your free course! Create your login now! Sorry, your blog cannot share posts by email. An example would be water.
Temperature affects its viscosity. The viscosity of water is certainly not affected by applied stress. Non-Newtonian fluids are fluids that no dot follow Newton's law of viscosity. An example would be ketchup. When you shake a bottle of ketchup, the sauce becomes more liquid. Now that we know how Newtonian fluids differ from non-Newtonian fluids, let's take a look at some common examples of non-Newtonian fluids.
Oobleck is easy to make and is commonly used to display the properties of non-Newtonian fluids. Oobleck is made from cornstarch and water, and the starch components are suspended in water which causes its unusual behaviour. When force is applied, the liquid turns into a solid. After the force is removed, the oobleck will return to its original state of liquid. Ketchup is the opposite of the oobleck described above.
For example, ketchup is much easier to squeeze out of a sauce bottle after you have shaken the bottle.
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