In our series of fun science experiments for kids to try at home, kindly provided by The School of Chemistry at NUI Galway, try this Non-Newtonian Fluid experiment where you will learn all about non-Newtonian fluids including ketchup, silly putty, and quicksand.
You will need:
- Some water (2 parts cornstarch:1 part water roughly)
- Food colouring (optional)
- Large tray to hold mixture.
What to do:
- Mix all of the cornstarch with some water, containing food colouring if using, with your hands until it resembles liquid.
- When touched and grabbed with your hand it should turn solid-like, this means it’s ready. This takes about 10-15 mins of good mixing with your hands to achieve this.
- The mixture will look like a liquid and move from side to side when the container holding it is tilted.
- Try to punch the liquid or grab the liquid into a ball. What happens?
How does it work?
When a pressure is applied to the mixture either by trying to punch the liquid or grab the liquid into a ball the fluid mixture becomes solid like. This is due to the sudden pressure your hand is applying to the mixture. Pressing your hand slowly through the mixture allows the mixture particles to move out of the way but sudden movements like punching the mixture does not allow the particles to slide past each other and out of the way out of your hand.
“Viscosity” is a term used to describe the resistance of a liquid to flow. Water, which has a low viscosity, flows easily. Honey, at room temperature, has a higher viscosity and flows more slowly than water. However, if you warm honey up, its viscosity drops and it flows more easily.
Most fluids behave like water and honey, in that their viscosity depends only on temperature. We call such fluids “Newtonian,” since their behaviour was first described by Isaac Newton. The cornstarch mixture is “non-Newtonian” since its viscosity also depends on the force applied to the liquid or how fast an object is moving through the liquid.
Other examples of non-Newtonian fluids include ketchup, silly putty, and quicksand. Quicksand is like the cornstarch mixture: if you struggle to escape quicksand, you apply pressure to it and it becomes hard, making it more difficult to escape. The recommended way to escape quicksand is to slowly move toward solid ground; you might also lie down on it, thus distributing your weight over a wider area and reducing the pressure.
The School of Chemistry at NUI Galway advise that adult supervision is needed for all experiments. The portions of materials used in the experiments should not be increased from that described and mixtures prepared should not be ingested. The full text should be read before starting any experiment.
Related : 5 Fun Science Experiments for Kids
Did you try this experiments? How did it go? Tell us in the comments below!