Snapping your fingers: How does it work?

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Photo by Kreative Kwame on Unsplash
Photo by Kreative Kwame on Unsplash

A snap of the fingers has been used for millennia for everything from communication to music to the extermination of half a fictional universe, but we still don't fully understand how we can do it. To help answer this question, international researchers filmed several people snapping their fingers in slow motion, generally at about 30 times the speed of the blink of an eye. The researchers believe the skin on our fingers has formed to create a form of spring through friction, building up energy for the quick release. When testing the finger snap using materials like thimbles and lubricated gloves, participants were unable to snap their fingers as strongly, suggesting the skin is an important part of the process.

Media release

From: The Royal Society

Feeling snappy - The ultrafast snap of a finger is mediated by skin friction

Despite being a near universal motion that humans have performed for centuries, the physics of a finger snap remain unexplored. By combining experiments and simulations, we show that human finger pads have an optimally tuned friction and compressibility which allow the finger snap to reach some of the highest angular accelerations observed in the human body. We find that the skin friction plays a dual role as a `latch’ in the ultrafast motion of a finger snap: maximizing the potential energy stored, while minimizing the energy dissipated by quickly releasing for a rapid motion.

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Research The Royal Society, Web page The URL will go live after the embargo ends
Journal/
conference:
Journal of The Royal Society Interface
Research:Paper
Organisation/s: Georgia Institute of Technology, USA
Funder: R.A. acknowledges funding support from Georgia Tech’s Presidential Undergraduate Research Award (PURA). M.S.B acknowledges funding support from NSF CAREER award no. 1941933. M.I. acknowledges funding support from the NSF for this work under grant no. 2019371.
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