A question :
Why is it possible to ice-skate at minus zero temperature?
This question has not yet been satisfactorily answered.
It had long been believed that the pressure of an object in
contact with ice causes a thin layer to melt. The hypothesis was that the blade
of an ice skate, exerting pressure on the ice, melts a thin layer, providing
lubrication between the ice and the blade. This explanation, called
"pressure melting", originated in the 19th century. This, however, did
not account for skating on ice temperatures lower than −3.5 °C and skaters
often skate at this lower temperature. In the 20th century, an alternative
explanation, called "friction heating", was proposed, whereby friction
of the material causes the ice layer to melt. However, this theory also failed
to explain skating at low temperature. In fact, neither explanation explain why
ice-skating is possible at below minus zero temperatures.
This postcard came from Katariina (18 July 2014) Postcrossing.
This postcard came from Katariina (18 July 2014) Postcrossing.
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