We all know what happens when you snap your fingers – it makes that noise! But have you ever wondered how that noise comes to be? It turns out that the noise is caused by a small quantity of air being released at around 160km/h, but until now nobody has been able to see it happen fast enough.
That’s why researchers from Stevens Institute of Technology, New York University, and Technical University of Munich teamed up to develop a high-speed camera to capture the process.
The experiment was set up with an LED light positioned about 100 centimeters away from the finger tip. When snapped, the LED lights up momentarily which allows for it’s speed and trajectory path to be measured.
The camera was set to take a snapshot of the air release at a rate of 13 frames per second, which allowed for a temporal image of the event to be captured, and also showed how fast it reached its maximum speed.
Today Every has some more information about New High-Speed Video rReveals the Physics of a Finger Snap.
Here are some points discussed-
1. Detailed Images of Air Release
The movie captured the release of the air from the fingernail at a speed of 160km/h. The experiment also revealed that the speed is actually lower at around 120km/h, as seen in this image. The speeds were measured directly by determining when the peak in air flow reached 165km/h.
2. Snap and Bang!
The researchers also observed that during the event, a transient sound was produced and felt by subjects, which is why they suggested it is more than just “the noise”, but rather “the snap”. One interesting aspect of this experiment is that they have shown just how much sound can be generated when a finger snaps.
3. Finger Snap Physics
They also observed some flow-reversal, which is a phenomenon that occurs when the air passes through a contraction of the finger tip, which creates a “bang” sound. They also noticed that there is an acoustic phase shift that happens between the snap and bang, which was an interesting observation to make as it demonstrates how slow events can be seen on video at high speed.
4. Popsicles!
If you’re wondering whether this process can be used to generate enough force to pop a cold treat out of its mold, you would be correct. This is only applicable for small popsicles though due to the cone shape of your finger tip.
The team hopes that their research will help to further our understanding of the physics behind snapping and cracking, which will hopefully lead to applications in other important fields such as medicine, where these processes are more commonly observed.
5. Methodology
The experiment was conducted on different subjects, who all produced different snaps. The researchers aimed to get a good snap from each finger, from which they then measured the peak speed of the finger snap. The experiment was repeated on the same subject several times to gather many snapshots at varying speeds.
Taken together, these snapshots provided a complete picture of air release and noise production at high-speed. Ultimately they were able to piece together the led lights path and movement in order to determine its velocity and trajectory.
6. Future Applications
These observations have also enabled researchers to better understand the noise that is produced during cracking and popping, which will help us to determine why they are such uncomfortable sounds to listen to. For example, a snapping noise is more irritating than the crackling of a fire due to the different processes involved, and we may be able to harness this theory in order to develop new ways of making less stressful sounds.
By studying these processes we can potentially use this information for future applications in medical treatment of cartilage or nerve damage.
The research will also allow us to investigate how these processes are affected by different properties such as changing pitch or loudness. We can potentially learn how these phenomena are affected by other factors such as temperature variation too.
7. Summary
The experiment was carried out on six subjects to test the same finger, and was found that the air speed reached a peak of around 165km/h. During this experiment, a transient sound was produced and felt by subjects which is why they suggested it is more than just “the noise”, but rather “the snap”. This snap is also accompanied by a wind-like “bang” noise which happens only once during the entire trial.
