Tuesday, April 15, 2014

A Non-Newtonian Side to Jack White

Jack White, former lead singer of The White Stripes band, recently released a music video of “High Ball Stepper” – a song off his new solo album Lazaretto – that takes advantage of the alien-like properties of non-Newtonian fluids. Although you won’t learn how the science behind the music video works from watching, you can certainly see the cool effects of non-Newtonian fluids while listening to White rocking out on his electric guitar. If, however, you do want to learn the science behind the scenes, then keep reading.



In the video, a gelatinous mixture is poured over speakers. The fluid then begins to bubble and dance to the beat of White’s tune. The volume and subsequent vibrations of the speaker increase as the song progresses, reaching max volume at about two minutes in. The variation in the strength of the speakers' vibrations gives you a nice look at both the liquid and solid-like properties of non-Newtonian fluids.

Toward the beginning of the song, the fluid looks as if it’s trying to boil. This is the result of interfering waves. Liquids will react to a force by creating waves. If those waves interfere, then you sometimes get raised localization points, which are the lumpy bumps that appear in White's video and the video below.



About two minutes in, you’ll see the fluid fly up for an instant. During that moment, it looks more like a composed pancake than a disjointed mass of water. This is the solid-like behavior that non-Newtonian fluids adopt when they experience a rapid force.

The difference between Newtonian and non-Newtonian fluids is how readily they flow – a property called viscosity. On a molecular level, Newtonian fluids flow more easily because the distance between molecules is large compared to the size of the molecules. Therefore, when a stone is dropped in a glass of water, for example, it sinks rapidly because the molecules have ample room to move out of the way of the object.

On the other hand, molecules of non-Newtonian fluids are more tightly packed. So, when you drop a stone in a glass of honey, the more tightly-packed molecules require more time to move around one another. Much like if you were trying to move an elephant through a room. The elephant will move slower in a crowded room and more quickly in a less crowded room.

You can actually transform a Newtonian fluid into a non-Newtonian fluid simply by introducing more particles into the empty space. A classic example of this is adding cornstarch to water. The video below shows a pool of cornstarch and water. If you stomp quickly enough, you can essentially "walk on water (and cornstarch)."



So, why do non-Newtonian fluids sometimes act like solids and sometimes like liquids? It has to do with the rate of the force applied, which brings us back to Jack White’s music video.

The louder the bass and overall volume, the more energy it applies to the fluid. If you apply a force fast enough to a non-Newtonian fluid, then the molecules will not have time to react. Instead of flowing around the object, the molecules will bunch up. That is why you can walk on a pool of cornstarch if you act fast.

Think about what would happen if you placed an elephant on roller skates and launched the animal into a crowded room. People would not have time to move out of the way and would instead become jammed against one another. As a result, the elephant would not be able to penetrate the crowd. The same principle goes for non-Newtonian fluids.

White’s video addresses another scientific property involving sound. You can learn more here.

2 comments:

  1. It's worth noting (for the science demonstrators out there) that rock music does not produce a dancing oobleck effect like the Jack White video suggests. In my experience, you really can only use a boring (and sometimes ear-piercing) tone through the speakers to get that effect.

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