With a quick click of their fingers, scientists have set a human speed record.
The most detailed study yet of the physics of a finger snap has shown that in terms of acceleration*, no other body movement comes close.
Research inspired by a Hollywood film looked at how the tip of the finger that is “clicked” traces an arc in the air as it moves from the tip of the thumb. Using high speed cameras, they found that it reached a speed about 20 times faster than the blink of an eye. It accelerated at 1.6 million degrees per second squared.
This “rotational acceleration” was nearly three times greater than the previous record for human anatomy*, set by a professional baseball player’s arm. Currently playing for the New York Yankees, Aroldis Chapman still holds the record for the fastest recorded pitch in major league history for a fastball he threw in 2010.
Dr Saad Bhamla, an assistant professor at the Georgia Institute of Technology in Atlanta, who studies “ultrafast motions” in living things, said: “I’ve been fascinated with how we can snap our fingers. It’s an extraordinary physics puzzle right at our fingertips that hasn’t been investigated closely.”
The research, published in the Journal of the Royal Society Interface, splits the finger snap into three phases. First, force is first built up by pressing the thumb and middle fingers together. This appears to be stored in springlike tendons* in the fingers and forearm.
Friction between the two fingers acts like a latch, preventing the energy from being released.
Eventually, an “unlatching” process begins, with the thumb moving sideways and the middle finger quickly sliding past the thumb, starting the snap motion. The middle finger then slips into the palm, generating shockwaves that result in a “pop” sound.
But back to Hollywood. The study was inspired by Avengers: Infinity War and the villain Thanos, who destroys half the universe by snapping his fingers. He does this while wearing a metal gauntlet*. When they saw this scene, Bhamla and his colleagues asked themselves if this was possible – could you snap your fingers while wearing a metal glove?
They explored the role of friction by covering fingers with different materials, including metallic thimbles*, which reduced friction. This interfered with the “latch” step of the snap and resulted in the speed of the fingers falling.
Increasing the friction of the fingertips with rubber coverings also reduced speed and acceleration. The researchers concluded that a “Goldilocks zone”* of friction was necessary. Too little friction and not enough energy was stored to power the snap. Too much friction led to displacement of energy as the fingers took longer to slide past each other, “wasting” the stored energy as heat.
John Howard Long of the National Science Foundation in the US, which funded the research, said: “These scientists have opened the door to discovering the principles operating in other organisms*, and to putting this mechanism to work in engineered systems such as bioinspired* robots.”
This story originally published in The Times and is reproduced with permission
- acceleration: act of speeding up, hastening, advancing
- anatomy: bodily structure of humans, animals and other organisms
- tendons: strong tissue attaching muscle to bone
- friction: force resisting the relative motion or movement or something
- gauntlet: armoured glove
- thimbles: small metal or plastic cap worn over the fingertip to protect it while sewing
- Goldilocks zone: inspired by the famous children’s story, this expression refers to conditions that are “not too hot, not too cold, but just right”.
- organisms: a living thing with one or more cells, capable of growing and reproducing
- bioinspired: based on biological structures or processes
- Which Hollywood film inspired this scientific study?
- The previous record for “rotational acceleration” was set by an athlete in which sport?
- How many times faster than the blink of an eye is the snap of the fingers?
- How many times greater than the previous record for human anatomy was the record speed?
- This mechanism could be put to work in what engineering system?
LISTEN TO THIS STORY
1. Write a story
Use the information in the story to write a step-by-step guide to finger snapping. Your guide must include drawings or illustrations and each step must include the scientific facts behind it. Your audience is kids who don’t know how to snap their fingers.
Time: allow 20 minutes to complete this activity
Curriculum Links: English; Science
Create a design for an invention inspired by this research. Your invention has to be something that you could use in your everyday life.
Time: allow 30 minutes to complete this activity
Curriculum Links: English; Design and Technologies; Science
Read with Kung Fu punctuation
Pair up with the article between you and stand up to make it easy to demonstrate your Kung Fu punctuation.
Practice reading one sentence at a time. Now read it again, while acting out the punctuation as you read.
Read and act three sentences before swapping with your partner. Take two turns each.
Now as a challenge ask your partner to read a sentence out loud while you try and act out the punctuation. Can you keep up? Swap over? Try acting out two sentences.
Are you laughing yet? Have fun acting out your punctuation.