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Researchers cut to the chase on the physics of paper cuts:
If you have ever been on the receiving end of a paper cut, you will know how painful they can be.
[...] To find out why paper is so successful at cutting skin, Jensen and fellow DTU colleagues carried out over 50 experiments with a range of paper thicknesses to make incisions into a piece of gelatine at various angles.
Through these experiments and modelling, they discovered that paper cuts are a competition between slicing and "buckling". Thin paper with a thickness of about 30 microns, or 0.03 mm, doesn't cut so well because it buckles – a mechanical instability that happens when a slender object like paper is compressed. Once this occurs, the paper can no longer transfer force to the tissue, so is unable to cut.
Thick paper, with a thickness greater than around 200 microns, is also ineffective at making an incision. This is because it distributes the load over a greater area, resulting in only small indentations.
The team found, however, a paper cut "sweet spot" at around 65 microns and when the incision was made at an angle of about 20 degrees from the surface. This paper thickness just happens to be close to that of the paper used in print magazines, which goes some way to explain why it annoyingly happens so often.
[...] ensen notes that the findings are interesting for two reasons. "First, it's a new case of soft-on-soft interactions where the deformation of two objects intertwines in a non-trivial way," he says. "Traditional metal knives are much stiffer than biological tissues, while paper is still stiffer than skin but around 100 times weaker than steel."
The second is that it is a "great way" to teach students about forces given that the experiments are straightforward to do in the classroom. "Studying the physics of paper cuts has revealed a surprising potential use for paper in the digital age: not as a means of information dissemination and storage, but rather as a tool of destruction," the researchers write.
Journal Reference: Sif Fink Arnbjerg-Nielsen, Matthew D. Biviano, and Kaare H. Jensen, Competition between slicing and buckling underlies the erratic nature of paper cuts, Phys. Rev. E 110, 025003 – Published 23 August 2024 DOI: https://doi.org/10.1103/PhysRevE.110.025003
(Score: 2) by looorg on Wednesday October 23 2024, @05:27PM (9 children)
But why does it hurt so much? Cutting myself, by accident, with other sharp implements, rarely hurt as much as when you cut yourself on a piece of paper. I stabbed myself with a chisel many years ago while doing some amateur woodworking, enough to leave a large mark on the hand where it went in that is still visible to this day, regularly cut myself in the tip of my fingers with scalpels while cleaning or working on plastic models, etc etc. But nothing hurts as much as a paper cut. I have not been stabbed with a knife or shot yet, so I hold on to hope that it will hurt worse if it would ever happen.
(Score: 3, Interesting) by krishnoid on Wednesday October 23 2024, @05:56PM (3 children)
Nerve density in the hands and fingers [britannica.com]? Probably more like pain receptor density.
(Score: 4, Interesting) by Unixnut on Wednesday October 23 2024, @06:23PM (2 children)
Not sure, the GP mentions cutting themselves on their fingers, just with different implements.
I can attest to cutting myself with paper and scalpels and other tools on my fingers in roughly the same area, and the paper cuts are the most painful.
I actually think it may be because the paper cut is not as deep as the others, so more of the nerves remain intact to send pain signals to your brain. When I cut myself with something like a knife it goes in deeper and may well sever the pain receptors before they fire. The result is a wound that is more numb and throbbing than with paper, which is just a sharp pain in my experience.
(Score: 3, Informative) by Gaaark on Wednesday October 23 2024, @08:36PM
Cardboard cuts are the worst: they can go deep and cut like a scalpel. Hurts like a bee-otch!
--- Please remind me if I haven't been civil to you: I'm channeling MDC. I have always been here. ---Gaaark 2.0 --
(Score: 4, Informative) by Anonymous Coward on Wednesday October 23 2024, @09:43PM
Paper is ragged and coarse. Compared to the knife, it's like sandpaper and fibers rubbing all those nerve endings, much more irritating than the nice smooth knife where you can cut yourself pretty deeply without noticing. Be grateful that paper isn't made out of wool
What happens if you cut yourself with a Paper Knife [youtube.com]?
(Score: 2) by Freeman on Wednesday October 23 2024, @08:59PM (2 children)
From what I understand, the sharper and finer the blade, the less it hurts, because it's more of a precision cut. Whereas a paper cut is by it's nature going to be more jagged than a scalpel and as mentioned below how cardboard paper cuts are the worst. More tissue damage, more pain.
Anecdotally, I can confirm that ripping a gash in your finger hurts a whole lot more than a paper cut. Having suffered from both. The paper cut hurt, but it also healed fine and wasn't so bad. Catching yourself from falling with a keyring around your finger, which then cuts a gash in your finger, hurts a whole lot worse.
Also, note instances of people not noticing they had a nail lodge itself in their nasal cavity. Weird stuff happens sometimes and you would really think some things would hurt enough to get checked out when it happens. As opposed to a few days later, due to a "continual headache".
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 2) by hendrikboom on Wednesday October 23 2024, @09:10PM (1 child)
In the nasal cavity -- do you mean a fingernail or a hardware-store nail?
(Score: 3, Interesting) by Freeman on Wednesday October 23 2024, @09:51PM
Not sure, if this is the one I remember, but it certainly could have been. It's been a while since I remember grazing past it in the news.
https://abcnews.go.com/blogs/health/2012/01/21/x-ray-reveals-nail-in-mans-brain [go.com]
This next one is not the one I remember, but seriously Nail guns can be dangerous. https://www.today.com/news/what-headache-man-survives-nail-skull-wbna25091319 [today.com]
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 3, Interesting) by Tork on Wednesday October 23 2024, @09:09PM
🏳️🌈 Proud Ally 🏳️🌈 - Give us ribbiti or make us croak! 🐸
(Score: 1) by shrewdsheep on Thursday October 24 2024, @07:36AM
And the cuts last long. My interpretation is that the cuts most of a time happen at an angle and are quite deep, exposing quite a large area. Together with the fact that the tissue is often in movement makes for both painful and slow-healing wounds.