In the video seen above, a liquid seems to transform into a solid when punched. Strange as it seems, such fluids are to be found in our everyday life as well. Known as non-Newtonian fluids, these liquids behave in unusual ways.
As the video shows, a finger swirling through the substance keeps it liquid, but when it is punched (that is, when more force is applied and over a larger surface area), it behaves like a solid.
Ketchup, while it does not become solid, is also a non-Newtonian fluid, as it becomes runnier when shaken. To achieve the result seen in the video above, one can mix cornstarch with water, and while it will be easily penetrable by a slow movement, it too will turn solid when punched.
Interestingly, when combined with an oscillating plate or a vibrating speaker, non-Newtonian fluids demonstrate other unusual properties, like protruding “fingers” and holes that persist after creating them. Here is a video of a non-Newtonian fluid on a speaker cone: