Quicksand is what scientists call a non-Newtonian fluid. If you look at it, it appears to be a solid. However, if something disturbs it and pressure is placed on it even slightly, then its viscosity will suddenly decrease. The viscosity of something is a measure of its resistance to stress. If you try to poke your finger through water in a glass, your finger will sink quickly to the bottom without much effort. Water has low viscosity. If you try to poke your finger through a glass full of honey, you’ll have a more difficult time reaching the bottom because honey has a higher viscosity. When an animal or human walks on top of quicksand, the added pressure lowers the viscosity, causing the quicksand to become more fluid so that you sink into it.
Growing up, I loved to read Dr. Seuss books. (If I’m honest . . . I still do!). In Seuss’ book, Bartholomew and the Oobleck, the king of Didd decides he is tired of normal weather. He asks his magicians to create a new and exciting type of weather. The next day, the kingdom is plagued with an ooey, gooey, sticky green mess that never ends . . . oobleck.
This oobleck is another type of non-Newtonian fluid. To explore with it at home, follow our recipe and guidelines below!
Make your Own Non-Newtonian Fluid – OOBLECK
Before You Start:
1. Pour your water into the mixing bowl. If you would like to make your oobleck colorful (or green like in the story!), you can add food coloring to the water at this point.
2. Slowly add 1 ½ cups of corn starch and stir with the spoon. As you stir, the mixture will begin to thicken. You will need to switch to mixing with your hands.
3. Keep adding additional corn starch as needed. If you quickly poke the oobleck with one finger, and your finger doesn’t immediately sink into it, then the oobleck is at a good consistency. If it gets too thick, you can always add more water.
- Oobleck is non-toxic. It is made with ingredients that are in foods you eat. However, be careful as you explore, and always wash your hands and your area of exploration after you are done.
- While the is still in the bowl, take one finger and quickly poke the oobleck. What happens? Now, take your finger and slowly swirl it around in the oobleck. Does it react any differently?
- Take a clump of oobleck and roll it into a ball. Let the ball rest on your outstretched palm or on the tabletop. Does it continue to behave as a solid after you have stopped rolling it?
- For even more fun, take a large plastic bin and make a giant batch of oobleck. Take off your shoes and socks and try walking through the oobleck. Can you walk on top of it without sinking? Can you wiggle your toes in it?
- The oobleck is a non-Newtonian fluid, just like quicksand. It changes quickly from liquid to solid based on how much pressure you apply.
- When you quickly poked the oobleck, the corn starch suspended in the water resisted movement (higher viscosity). However, when you slowly swirled your finger through the oobleck, you gave the corn starch particles more time to move out of the way, so the viscosity did not change as much. Quick, high pressure makes oobleck appear more solid than liquid. Slow, low pressure makes oobleck appear more liquid than solid.
- You have now experienced the properties of quicksand without having left your home!
- To avoid any younger siblings or pets getting stuck in your oobleck experiments, please make sure to clean up after yourself.
- Make sure you mix any remaining oobleck in you bowl with plenty of water before dumping it down the drain.
- Wipe up any dried out oobleck off surface with a dry towel. Then, take a damp towel or sponge to get anything that remains.