Walk (or run) on water using science:
Have you ever tried to walk on water? Chances are, you failed (and no, ice skating doesn’t really count). Why did you fail? Your density is much higher than that of water, so you’ve sunk. However, other organisms can walk on water. If you apply a little science, you can too. It is a great science project for children of all ages.
Materials for walking on water using science :
- 100 cans of cornstarch
- 10 gallons of water
- small plastic children’s pool (or large plastic bathtub)
What are you doing?
- Go outside. Technically, you can do this in your bathtub, but chances are you are clogging up your pipes. In addition, this project quickly becomes a mess.
- Pour the corn starch into the pool.
- Add the water. Mix it up and experiment with your “water”. It’s a good opportunity to find out what it’s like to get stuck in quicksand (without the danger).
- When you’re done, you can let the cornstarch settle on the bottom of the pool, remove it and throw it away. You can water everyone with water.
How it works?
If you walk slowly through the water, you will sink, but if you walk quickly or run, you will stay above the water. If you walk on the water and stop, you will sink. If you try to pull your foot out of the water, it will get stuck, but if you pull it slowly, you will escape.
What is happening? You basically made homemade quicksand or a giant oobleck pool .
Corn starch in water has interesting properties. Under certain conditions, it behaves like a liquid, while under other conditions, it acts like a solid. If you hit the mixture, it will be like hitting a wall, but you can run your hand or body over it like water. If you press it, it feels firm, but when you release the pressure, the liquid flows through your fingers.
Newtonian fluid is a fluid that maintains constant viscosity. Corn starch in water is a non-Newtonian fluid because its viscosity changes with pressure or agitation. When you apply pressure to the mixture, you increase the viscosity, which seems more difficult. Under lower pressure, the fluid is less viscous and flows more easily. Corn starch in water is a thickening shear fluid or a dilating fluid.
The opposite effect is seen with another common non-Newtonian fluid – ketchup. The viscosity of ketchup is reduced when it is disturbed, which is why it is easier to pour ketchup in a bottle after shaking it.