Thanks to Brilliant for supporting  this episode of SciShow. Go to Brilliant.org/SciShow to learn how you can take your STEM skills to the next level this year! A snap of the fingers is a  metaphor for something easy. Like, you can do it in a snap. But researchers who really buckled  down to study the physics of finger snapping found... it’s  actually a pretty impressive feat. And understanding it could help us study  things from insect jaws to prosthetics. In a study published in 2021 in  Journal of the Royal Society Interface, researchers figured out the  physics of the finger snap using high speed cameras and force sensors. The inspiration for the study  came after seeing a movie where the villain snaps his fingers  while wearing a metal glove. Six guesses for which one that is. The researchers wondered  whether that would be possible, because the metal wouldn’t have much friction. Well, according to the study,  the perfect snap can be broken down into three phases. The first is loading, where  the thumb and middle finger store up kinetic energy, or energy of motion. Then comes the unlatching, where the  fingers start to slide past one another. And finally, unlatching movement  is when the fingers move at ultra-fast speeds until the  middle finger hits the palm, creating shock waves that make the ‘snap’ sound. The whole thing happens in  less than 7 milliseconds, 20 times faster than the blink of an eye. And during that unlatching movement  phase, your fingers are rotating at up to 7,800 degrees per  second, almost as fast as a professional baseball player  rotates their arm during a pitch. All this means, finger  snapping is one of the fastest, most explosive movements our bodies can muster! But whether those three phases add up to a snap or silence comes down to one key element: friction. Friction is the resistance between  two objects moving over one another. And it turns out that snapping requires  a sort of Goldilocks zone of friction. You see, you want friction to help build  up the kinetic energy in the loading phase.

But you have to overcome the friction when it comes time to release during unlatching. Researchers figured out just  how much friction contributes to snapping by rigging how slippery  and squishy a person’s fingers were. To make them more slippery, participants in the study wore lubricated nitrile gloves. And when they did, their  fingers didn’t create enough friction and they could not store up  enough energy for a forceful and loud snap. If their fingers were instead made more  grippy by wearing a latex rubber glove, then participants couldn’t release  their fingers and the snap also flopped. The researchers also wanted to see whether the squishiness of someone’s fingers,  or how compressible they were, had anything to do with  the friction that built up. So some participants wore a hard metal  thimble with a nitrile glove on top. And it turns out fingers  need to be at least a little squishy to help build up that friction. So snapping with a metal glove  on? Not possible for people. Maybe possible if you have  infinity stones or something. The researchers, who had previously  studied super-fast motion in other animals, took all this  information and combined it into a mathematical model that could now be  used to help in other fields of science. For example, it could help biologists  understand the snaps of, say, Panamanian termite soldiers. Those are insects that snap their jaws  together ultrafast to defend their hive. And the researchers propose the mechanism  might be similar to finger snapping. Plus, understanding the  dynamics of the finger snap could help engineers fine tune  the movement of prosthetics. Which you gotta say, isn’t just fun, but  pretty snappy research indeed. It’s funny how we don’t really understand  things like finger snapping until someone goes “But how does that actually work?” and they decide to do some science about it. But to learn more about the physics of  the everyday, from bridges to fridges, you might like Brilliant’s  course Physics of the Everyday.

Or any one of the math, science,  engineering, and computer science courses they have available. Because if you’ve decided you want  to learn new things in the new year, Brilliant is a great resource. Their interactive courses focus  on letting you participate rather than learning by rote. Right now, if you sign up at  brilliant.org/scishow, you can save 20 percent off an annual premium subscription to Brilliant. And checking them out also helps us so thanks.