Is Oobleck Liquid or Solid?

When you are in the middle of quicksand, what will you do? Run quickly cross it or walk gently cross it. This fabulous experiment will tell you what you should do. You also can find a lot of fun while playing it.

Age：8+      Time: < 30mins

 Safety 

1. Play in the tray.
2. Be careful with the fragile glass.
3. Wear protective goggles.
4. The liquid should be discarded in one day.

 Materials list 

• 100g corn starch
• Water
• Food coloring (optional)
• Tray or a big bowl
• Glass rod
• Goggles

 Instruction 

Step 1/2 – Add 100g of starch and 70ml water in a bowl. You also can add a few drops of food coloring to achieve the colorful liquid.

Step 2/2 – Mix them well. Then you have your Oobleck.

 Troubleshooting 

Why does the Non-Newtonian fluid not work after a period of time?

- After a period of time, the starch will separate from water.
- All you need is stir it.

 Question to ask 

1. What is the difference between a hard punch in non-Newtonian fluid and a gentle one?
2. Do you know in our daily life if there are other Non-Newtonian fluids?
3. Do you know in what field the trait of Non-Newtonian fluid can be applied for?

 Scientific description 

A non-Newtonian fluid is a fluid that does not follow Newton's law of viscosity, that is to say, constant viscosity independent of stress. In non-Newtonian fluids, viscosity can change when under force to either more liquid or more solid. non-Newtonian fluids can be found in daily life. For example, the longtime stand ketchup is more solid and when ketchup is turned upside down, the ketchup will hardly flow out, but when the ketchup is shaken, it will become more liquid and easily flow out. The toothpaste is almost in a solid form when it is standing, and when a proper force is given, it becomes more fluid and can be pushed out. In a non-Newtonian fluid, the relation between the shear stress and the shear rate is different. The corn starch and water mixture in this experiment is a non-Newtonian fluid with a higher shear rate accompanied by a higher viscosity, so you quickly punch in the starch and water mixture without breaking it. It will become very hard. Even if a hammer is used to hit it, there is no way to break it.

 Extensions 

You can put the non-Newtonian fluid into a special balloon which can be hard when you treat it hard and gentle when gently. You need to do this with a balloon of good quality in case the balloon is broken.

 Disposal 

Pour the mixture into the sink with a good deal of water and do not forget washing what you have used.