Oobleck! (Non-Newtonian Fluids)
Oobleck got its name from the sticky substance featured in the 1949 Dr. Seuss book Bartholomew and the Oobleck.
Today's oobleck is pretty cool because sometimes it acts like a liquid and sometimes like a solid, depending on how much pressure you put on it.
In the 1700s Isaac Newton described how fluids flow, and his ideas worked for stuff like water, milk, and wine. They're called Newtonian fluids, and they move out of the way pretty quickly when you push them--like a splash or a wave.
Newton's model doesn't work so well for other materials, like ketchup, quicksand, and oobleck. These are non-Newtonian fluids, and they have a high level of viscosity, or resistance to flow.
If you slap oobleck with your fingers or squeeze a handful, it will feel and act like a solid. The more you apply pressure, the thicker it gets.
If you stir oobleck gently with your fingers or open an oobleck-filled fist, it will feel and act like a liquid.
You can make your own oobleck at home and experiment with it!
-1 cup of water
-1.5 to 2 cups of corn starch
-Food coloring (and possibly rubber gloves to avoid stains on your skin)
1. Put the water in a bowl and mix in the corn starch. (It's O.K. to use your hands for mixing if it gets too tough to mix with a spoon.) Although there's science in oobleck, making it isn't an exact science; you can add more water or more corn starch if it feels like it needs it.
2. Add a drop or two of your favorite color, or combine different drops of color to make a new shade or experiment with swirls.
You might try:
- squeezing a blob in your fist
- rolling oobleck into a ball
- placing a plastic animal on the oobleck and seeing if it stands or sinks
- scooping up bits with a spoon and observing how oobleck behaves differently than pudding or oatmeal
- spreading oobleck on a cookie sheet and tracing letters or your name
- walking on oobleck (you’d need a BIG container and lots of oobleck)
- resting your hand on the surface, letting it sink to the bottom, then jerking it out
- putting a cookie sheet spread with oobleck on top of a stereo speaker and playing different styles of music
4. Store oobleck in an airtight container in the refrigerator when you’re done for the day.