What is Oobleck?
Oobleck is a white colored substance which normally behaves like a liquid However, when a strong external force is applied, it starts exhibiting characteristics of a solid. Confusing??!!
Some background knowledge:
There are three states of matter. Solid, Liquid & Gas. Well’ there’s another one: Plasma. Let’s keep it aside for the time being. Changing of states is a common phenomenon. On varying temperature, a solid might turn into liquid & then gas or rather directly to gas (sublimation). Also, a liquid might change into solid or a gas might turn into liquid. Change of states is also possible on varying pressure. Substances like oobleck change states on application of pressure.
Let’s take some practical examples. Immersing a hand into oobleck feels like putting it in a very dense liquid. On the other hand, hitting its surface very hard feels like hitting concrete. Let’s dwell a little deeper into what actually happens.
Behavior of Oobleck:
At the point on the oobleck where stress is applied i.e. where it is hit, viscosity increases rapidly & as a consequence, the oobleck behaves like a solid body. If you had a swimming pool filled with oobleck, you could easily run on its surface from one side of the pool to the other. If you stop somewhere in the middle of the pool, you would start sinking.
Oobleck is a non-Newtonian fluid. The viscosity of non-Newtonian fluids changes when shear or tensile stresses are applied on them. There are two types of viscosity changes:
a. Shear thickening: Viscosity increases with increased stress. Also known as Dilatant fluids. For example: Oobleck
b. Shear thinning: viscosity decreases with increased stress. Also known as pseudo plastic fluids. For example: blood, ketchup etc
How to prepare Oobleck?
Corn starch is the primary ingredient which is readily available at home. Oobleck is made of corn starch & water, mixed in a suitable ratio.The process is simple. Get the below mentioned ingredients & prepare your own Oobleck within minutes.
3.Any container, for example: a bowl
5.Food coloring (Optional)
Step 1: Mix well, Maxwell!
Follow the 2:1 principle. Add 2 parts of cornstarch to 1 part of water which means add twice as much cornstarch as water. Add few drops of food coloring if you want it to be vibrant. The best way to mix is to slowly add corn starch into the container with water and gently mix with a spoon until mixing becomes noticeably difficult.
At that point try poking (with extra force) the surface of the liquid with your finger. If your finger can’t push into the liquid, the oobleck is ready to use. Otherwise, add some more starch & keep stirring.
Step 2: Playing with Oobleck
Oobleck is non-toxic. It can be used by kids as play dough. It can be used by children in science fairs at school. It can be equally enjoyed by adults in kitty parties or team building activities.
Step 3: Cleaning Up
Cleaning part is important too. Oobleck is really messy. Wipe up any dried cornstarch with a dry cloth before cleaning up any remaining residue with a damp sponge. You can also use a damp paper towel & dry paper towel alternatingly.
Step 4: Left over Oobleck?
Oobleck will dry out if left overnight, but the good thing is it can always be re-hydrated. Just add more water until it gets to the desired consistency. You might also want to wash the oobleck down the drain. Just make sure that you Add plenty of extra water to the mixture before pouring it down the drain.