With summer glowing on the horizon, it’s time to start thinking about getting outside. There is no better time to try a classic experiment that you may want a hose to clean off from!
This month we examine something tricky – a non-Newtonian fluid. This is a fluid that doesn’t behave as a fluid should. Sometimes it may flow, but sometimes it reacts like a solid. All you need are cornstarch and water, and a place you can make a mess.
Instead of prescribing a set quantity of cornstarch and water to combine together, try starting with one and adding the other until you come to a consistency you like. This adds some experimentation into the activity, and kids can decide what the best ratio (if you measure as you work) of water to cornstarch is for maximum fun. When Discovery Centre staff bring out a wading pool full of the stuff at special events (outdoor events!), they always begin with cornstarch and add water because water is generally more freely available. Add water slowly, and start with less than you expect – it takes surprisingly little!
The strange behaviour of the mixture of cornstarch and water has to do with the shape of the particles of cornstarch. The particles don’t slide past one another easily, and if they are forced to slide too quickly, they may lock together and trap water inside of the tangle they create. At these moments, the stuff (some people call it ‘oobleck’) behaves as a solid. You can squeeze it hard and create balls, and then tear them apart, but as soon as you let the mix relax, it will flow easily through your hands.
It isn’t recommended for eating, especially after it has been played with, but it’s totally non-toxic as both ingredients are safe to eat!
If you haven’t made summer plans for your family yet, don’t forget to check out our summer science camps, supported by Pratt & Whitney. They fill up quickly every year, so it’s worth checking our website or giving Danielle a call at 492-4422 x 221.