Curling…

First an update:
I have not forgot or abandoned this blog :)
But I'm in the midst of working on new home for it, and I have big back log of puzzles accumulated…

Here is intersting observation in relation to passed olympics:

If you put glass upside down and then give it a clockwise spin and slide it straight forward along the dry surface (bar stand for example) then glass will tend to go left. However if surface is wet it will tend to go right. Why is that ?