What puts the curl in a curling stone? This is a question that has interested me for about 10 years. Since Uppsala university is now involved in both cold fusion and curling the first tenuous link has been made between the two fields. ;-) As the article points out many explanations have been proposed and they all have shortcomings. The creators of this newest explanation seem overlook the force required to _carve_ the scratches at the leading edge. This activity, I think, would tend to make the stone curl in the opposite direction or at least cancel the effect of the curling force produced by the scratches on the trailing edge. Harry
The mechanism that puts the curl in curling revealed http://phys.org/news/2013-05-mechanism-stone-revealed.html quotes: <<Researchers from Uppsala University in Sweden can now reveal the mechanism behind the curved path of a curling stone. The discovery by the researchers, who usually study friction and wear in industrial and technical applications, is now published in the scientific journal Wear.>> <<As the stone slides over the ice the roughness on its leading half will produce small scratches in the ice. The rotation of the stone will give the scratches a slight deviation from the sliding direction. When the rough protrusions on the trailing half shortly pass the same area, they will cross the scratches from the front in a small angle. When crossing these scratches they will have a tendency to follow them. It is this scratch-guiding or track steering mechanism that generate the sideway force necessary to cause the curl.>> Read more at: http://phys.org/news/2013-05-mechanism-stone-revealed.html
