Here is an interesting article taking claiming that the reason why ice-skaters can skate on ice is not that pressure exerted by the person lowers the melting point of the ice, melting the ice to allow the ice-skater to glide on a thin layer of water, which refreezes when the ice-skater passes.
http://www.nytimes.com/2006/02/21/science/21ice.html?th&emc=th
Article Title: “Explaining Ice: The Answers Are Slippery”.
Date: 21st February 2006
Publisher: NYTimes
The article talks about Dr. Rosenberg, “an emeritus professor of chemistry at Lawrence University in Appleton, Wis., and a visiting scholar at Northwestern University” who claims this:
“According to the frequently cited — if incorrect — explanation of why ice is slippery under an ice skate, the pressure exerted along the blade lowers the melting temperature of the top layer of ice, the ice melts and the blade glides on a thin layer of water that refreezes to ice as soon as the blade passes.”
He also claims that “
“People will still say that when you ask them,” Dr. Rosenberg said. “Textbooks are full of it.” But the explanation fails, he said, because the pressure-melting effect is small. A 150-pound person standing on ice wearing a pair of ice skates exerts a pressure of only 50 pounds per square inch on the ice. (A typical blade edge, which is not razor sharp, is about one-eighth of an inch wide and about 12 inches long, yielding a surface area of 1.5 square inches each or 3 square inches for two blades.) That amount of pressure lowers the melting temperature only a small amount, from 32 degrees to 31.97 degrees. Yet ice skaters can easily slip and fall at temperatures much colder. The pressure-melting explanation also fails to explain why someone wearing flat-bottom shoes, with a much greater surface area that exerts even less pressure on the ice, can also slip on ice.”
He also introduced to us 2 new theories that can explain how ice skaters skate on ice. “One, now more widely accepted, invokes friction: the rubbing of a skate blade or a shoe bottom over ice, according to this view, heats the ice and melts it, creating a slippery layer.”. The other is “The other, which emerged a decade ago, rests on the idea that perhaps the surface of ice is simply slippery. This argument holds that water molecules at the ice surface vibrate more, because there are no molecules above them to help hold them in place, and they thus remain an unfrozen liquid even at temperatures far below freezing.”
There are also other scientists mentioned discussing this topic.
his article is worth the read and you can purchase a copy at the URL porvided above if you are interested.
