Fun with Oobleck

Contributed by Austin Hopkins

Introduction

You may have learned about the states of matter – solid, liquid, and gas. But you may have seen quicksand in a movie or on TV, where a character thinks they’re on solid ground only to find themselves sinking! In this experiment, we will make a material similar to quicksand and see that some things don’t fit neatly into the category of solid, liquid or gas.

Materials

Procedure

Add the cornstarch in a medium sized bowl.
Slowly add the water, using your hands to mix it.
When you can ball the material together and feel it flow between your fingers, you will know that you are done.
Have fun playing with it! Try hitting it and then slowly pushing into it to see if it feels different.
When you are done, you can store it in a sealed container in the refrigerator for future use. If you want to dispose of it, make sure not to put it down the sink!

Physics Concepts and Questions

When you quickly hit the oobleck, does it feel like a solid or a liquid?
What about when you slowly push into the oobleck, does it feel like a solid or a liquid?
Try pressing it into a ball with your hands. When you hold it tight, does it feel like a solid or a liquid? What happens when you loosen your grip?

Conclusions and Further Investigations

There is another material you may have at home that is sometimes like a solid and sometimes like a liquid – ketchup! If you very lightly tap glass a bottle of ketchup, it stays inside like a solid would. But, if you hit it hard enough, it becomes like a liquid. This is why sometimes way too much can pour out all over your food!