Impossible, right? If you could walk on water you can at least guarantee that you have impressed your crush, so lets see if we can bend the rules a bit to put a smile on her face! What can we do in order to be able to walk on water?
Properties of Liquids
We need to understand some properties of liquids to find out how we can potentially overcome the problem of walking on water.
Viscosity
Viscosity is simply a measure of how thick a liquid is. The higher the viscosity the thicker the liquid. For example, ketchup is more viscous than water.
Surface Tension
Surface tension is the force created due to molecules in the surface of an object being attracted to each other. In our case, this object is water. The attraction of like molecules is known as cohesion. In our example this is the attraction of water molecules.
How do insects run across water?
In case you didn't know, some insects are capable of doing this - but how? It is time to apply what we now know about surface tension. When an insect steps on a body of water, the forces due to cohesion of water molecules are larger than the weight of the insect itself. This allows for some of them to walk on water as effortlessly as they do on land!
So, why can't humans walk on water?
Humans are so big and heavy that the force they impose on the water once they stand on it is a lot larger than the force of surface tension mentioned above. Hence, the human sinks.
How can humans walk on water then?
Non-Newtonian fluids
We are all aware that matter can exist as a solid, liquid, or gas - but what if matter can behave as more than one state at the same time.
What is a Non-Newtonian fluid?
These are substances that don't behave like we expect them to. For example, with Newtonian fluids, we expect the viscosity (mentioned above) to be constant. This is not the case with Non-Newtonian fluids.
Depending on varying forces or pressures applied to them; Non-Newtonian fluids flow at different rates. An example of a Non-Newtonian fluid would be 'Oobleck' which can be made in the comfort of your own kitchen!
How to make Oobleck
All you need to do is have some water in a container of your choice, and slowly add cornstarch a bit at a time whilst stirring. Keep doing this until the solution goes gooey and hopefully, you have made your first ever Non-Newtonian fluid!
What relevance does this fluid have?
Generally speaking, the larger the force or pressure you apply to this solution, the more it acts like a solid. Once you remove this force, it behaves like a liquid, so applying this knowledge...
Surely this means humans can walk on water... mixed with cornstarch, right? Since we are so heavy, our forces acting on the surface of this Oobleck should mean that it acts as a solid upon impact, correct? See below this incredible video, for yourself.
