As anyone who has ever attempted a pirouette on ice skates will know, ice is very slippery. This may appear obvious, but the reasons for the slipperiness of ice are not clear. Luca Canale and co-workers have now investigated the microscopic mechanisms behind the low friction of ice and have found that it is caused by the high viscosity of the meltwater layer between the sliding object and the ice surface.
The team simultaneously probed the friction and the mechanical properties of the meltwater film as it formed when a bead slid over the ice. The viscosity of this film can be up to two orders of magnitude higher than that of water that has been cooled to 0 °C. They also found that the film has a viscoelastic response that — coupled with the high viscosity — causes the slipperiness of ice. This result points to the need to consider complex rheology for ice friction models, rather than relying on the Newtonian descriptions that are currently used.
About this article
Cite this article
Dubrovina, E. Slippery ice. Nat. Phys. 15, 1210 (2019). https://doi.org/10.1038/s41567-019-0752-9