I had a chance to go to Hokkaido the other day, and it was much slippery the morning after it snowed than on the day it snowed. The pressure of the accumulated snow and the cold at night cause it to freeze and become slippery. I realized how stable the ground is without ice, and how grateful I am for the friction of the ground. It’s a bit surprising, but the reason why ice is so slippery has only recently been explained. Apparently friction creates a layer of water several hundred nanometers to one micrometer thick, and this layer is made of oil-like water that is viscoelastic and sticky.
https://engineer.fabcross.jp/archeive/191128_why-is-ice-so-slippery.html
This is also a story on ice, but curling is a sport where players slide stones across the ice to compete for points. Apparently, it was a mystery of the century as to why these stones curve. They turn when minute collisions between the ice and the bottom of the stone occur asymmetrically. Perhaps it has become possible to observe minute movements in the last 100 years, and these mysteries are being uncovered one after another.
https://www.rikkyo.ac.jp/news/2022/09/mknpps0000020uo9.html
To begin with, even modern research does not fully understand the phenomenon of friction. You can only know under what conditions and how much static friction a material experiences by conducting experiments. It also seems difficult to calculate the frictional force acting between materials. In real life, you can feel friction when you hold a cup or brake, so the existence of friction seems very natural to me. Even if we don’t understand the principles, I believe that everyday life would not work without friction, so I want to respect the existence of friction.
https://gendai.media/articles/-/132819?page=2
Looking into other examples besides friction, we find that there is crustal movement, where when a plate sinks, it drags in adjacent plates due to friction. So crustal movement is also a result of friction.
https://www.jishin.go.jp/resource/column/2011_1108_02
In addition, friction occurs between the ocean floor and the seawater that moves with the ocean tides, and this is called tidal friction. This friction causes the Earth’s rotation to slow down little by little. So water also creates friction. Is this because of the large scale?
https://astro-dic.jp/tidal-friction/
And there is also a story that the surface of the earth is protected by meteorites from space burning up due to frictional heat with the atmosphere. Is it something like a friction barrier? The frictional force of the atmosphere is amazing.
https://www.kahaku.go.jp/exhibitions/vm/resource/tenmon/space/a-c-m/a-c-m05.html
Although there are many unknowns, we are benefiting from friction without even realizing it. Our daily lives depend on friction. Friction is amazing. The Earth is amazing.
