Fun with Oobleck
Contributed by Austin Hopkins
- 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.
- 1 cup cornstarch
- ½ cup water
- Optional: Food coloring (be careful of staining!)
- 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!