What’s Non-Newtonian Fluid? Imagine a similar concept to quicksand…. It’s liquid, yet also solid due to suspended particles. In other words, it’s goo.
Viscosity of fluids
Sir Isaac Newton stated that viscosity, or how resistant a fluid is to flow, depends on the amount of heat applied. A non-Newtonian fluid, such as quicksand, or the goo you will make, has a viscosity that is affected by force, not heat. Honey, a Newtonian fluid, becomes more runny when it is heated, so it has a lower viscosity than cold honey. However, a non-Newtonian fluid’s viscosity lowers, and the fluid becomes more solid, when force is applied.
The goo you are about to make is actually a suspension, since the cornstarch and water will eventually separate from one another. The particles of cornstarch are floating throughout the water with relatively even spacing between each one. This is similar to the way sand particles are suspended in water in quicksand. Applying force causes the particles of cornstarch to become pressed tighter together, thus increasing the viscosity. This is also what makes escaping from quicksand a difficult task.
What you’ll need to make the goo at home:
- One 16 ounce box of cornstarch
- Food coloring (optional)
- Large bowl
- Measuring Cups
- Metal Spoon
- Casserole dish, cookie sheet, or something similar with sides
- Gallon zipper-lock bag
- Newspaper to cover work area for easy clean up
Mixing the goo
For a small batch of goo, place a 1 cup of cornstarch in a large bowl and slowly add ¼ cup of water. Stir the water in with the spoon as you pour it. Adjust the consistency of the mix by either adding more cornstarch or water. The final product should have the same viscosity as honey. Test it by using the spoon to scoop up a small amount of mixture and letting it drizzle back into the bowl.
If you want to make a large batch, dump the entire box of cornstarch in the bowl and add 1 full measuring-cup of water. You may need more water, but make sure to stir it well before adding any additional water. Mix it with your hand if you don’t mind getting a bit messy. Add the food coloring at any time. Use the spoon to stir it in if you are worried about the dye getting on your hand.
Observing Non-Newtonian fluid
Now comes the fun part; slowly let your hand sink into the bowl of goo. Take your hand out as fast as you can and see what happens. Was your hand held fast by the goo? Did the goo crumble and break? It’s fun to play around with objects in the goo as well. Collect a variety of small items and see how long it takes each one to sink. Try dropping a marble into the goo from a reasonable height.
Pour the fluid mixture onto a cookie sheet with sides on it or a large casserole dish. Notice how the goo pours easily into the new container? Now perform a slap test on the goo to see just how sturdy this liquid goo can be. Lightly slap the surface of the goo; not too hard or it could hurt! Did you expect the goo to be sturdy or give way? Experiment with the goo a bit more and then place the leftovers in a resealable plastic bag. The goo won’t last forever, but you’ll be able to enjoy it at least a few more times.
Clean up Tips
Don’t pour the goo down the drain without running water or the drain will clog. Fill all containers with water to reduce the consistency of the goo and turn the faucet on as you empty each container down the drain. If you decide not to use the leftover goo, toss the entire plastic bag into the trash. Allow the faucet to continue running for a bit to make sure all the goo has been washed down. Non-Newtonian goo is fun to play with, but a clogged drain takes the fun out of any experiment.
Decoding Science. One article at a time.