Chemistry - How does iceskating work?
Calderon & Mohazzabi give an excellent summation of the various theories proposed through the years to explain why ice is so slippery in their 2018 paper "Premelting, Pressure Melting, and Regelation of ice revisited" in the Journal of Applied Mathematics and Physics.
They offer both theoretical and experimental evidence that neither pressure melting nor friction melting explain the phenomenon and conclude from atomic force microscopy, among other evidence, that there is a pre-melting Quasi-Liquid surface layer with special properties that make ice skating possible.
- Calderon, C. and Mohazzabi, P. (2018) Premelting, Pressure Melting, and Regelation of Ice Revisited. Journal of Applied Mathematics and Physics, 6, 2181-2191. doi: [10.4236/jamp.2018.611183.]
Preview/read online at : https://www.researchgate.net/publication/328766489_Premelting_Pressure_Melting_and_Regelation_of_Ice_Revisited
There's a very nice—and fairly accessible—discussion of your third question in Nature Magazine's News and Views Section. In this article, Bonn discusses the results of a fairly recent work that appeared in Physical Review X. Bonn summarizes the key points as follows:
The idea that a thin film of meltwater wets the surface of ice has been accepted since the nineteenth century...[but]...Water is not a good lubricant, because its low viscosity means that it is easily squeezed out of gaps. The idea that a layer of water is sufficient to lubricate a skate on ice is therefore strange. It doesn’t even make intuitive sense, given that it is impossible to skate on a road or a kitchen floor with a layer of water on it...[The explanation thus seems to be that water and ice together]... form a viscoelastic, liquid–solid third body in response to friction and wear. (Emphasis mine)
Bonn, Daniel. The physics of ice skating. Nature 577, 173-174 (2020). link: https://www.nature.com/articles/d41586-019-03833-5
Canale, L., Comtet, J., Niguès, A., Cohen, C., Clanet, C., Siria, A. and Bocquet, L. Nanorheology of interfacial water during ice gliding. Physical Review X, 9(4), p.041025 (2019). link: https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.041025