Q. Why can we ski and skate on snow and ice?

A. Since ice and snow are solids, we would not be able to ski or skate smoothly on them as they are. It only becomes possible for us to slide easily as ice and snow melt to water.

In the case of skating, the metal blade of the ice skates we wear is very thin and when we place all of our weight on it, the pressure on the ice surface is very substantial. Since the melting point (the temperature at which a solid becomes a liquid) of ice lowers by approximately 0.0075 degrees Centigrade with each increase of one atmospheric pressure, the ice directly under the skates melts because of the pressure, which allows skates to glide.

In the case of skiing, the pressure on the ski and the heat caused by friction between the ski and snow melt snow, enabling the skis to glide. However, since it becomes more difficult to ski if the water spreads too much under the ski, there are gutters on the bottoms of skis to channel water away and we wax skis to repel water.