Mad Science Goo

October 1, 2009 by  


Mad Science Goo
Experiment: Investigate a very different kind of liquid

In the 17th century, Sir Isaac Newton conducted experiments with liquids and declared that all liquids have a constant thickness. Well, he never played with Mad Science Goo!

This slime, which you can make at home, takes the shape of whatever container it is in (like a liquid), but can also act like a solid.

What You Need
Large bowl
Measuring Cup
Food coloring (optional)

What To Do
Lay some newspaper under your work area. This could get messy.

Place a bowl in the center of the newspaper.

Pour a cup of cornstarch into the bowl. Add a few drops of food coloring if you wish.

Slowly pour some water (start with 1/2 cup) into the bowl, mixing the water and cornstarch together until all the powder is wet.

Keep adding water, little by little, until the mixture feels like a liquid when slowly mixed.

Try tapping on the surface with the back of a spoon. When the Goo is just right, it won’t splash like you would expect; it reacts like a solid! If your Mad Science Goo is too powdery, add a little water and mix again. If it’s too wet, add more cornstarch and mix.

Pick up a handful and squeeze it. Stop squeezing all of a sudden. What happens? What did you notice?

— Carole Jevons, Mad Science of Yakima County

What’s Going On?
The mixture feels solid when squeezed but flows like a liquid when released. This is because Mad Science Goo is a non-Newtonian fluid. This means that it does not have the same properties that most other fluids do (the ones described by Newton). Non-Newtonian fluids all share a unique property: Their thickness changes in response to pressure!

When you tapped the goo with the back of your spoon, you caused a sudden increase of pressure on the surface of the goo and the goo thickened. If you move your hand quickly through the goo, it resists your movement by becoming even thicker.

Did You Know?
The same principle applies to quicksand. If you ever find yourself trapped in quicksand, move very slowly toward the shore. The quicker you move, the thicker the quicksand will become around you, causing you to sink even further.

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