Question

The use of skis helps a person to slide smoothly over snow because, the skis .

Answer 1

Skis are large and flat sheets of objects that are used to glide over snow. These are generally made up of light metal sheets or woods and sometimes even of Carbon Fibers (an alloy of carbon and steel which is very light in weight and extremely strong). These make it possible for us people to travel from distance to another without too much effort.

Complete step-by-step answer:
Now, to understand how a ski helps us slide smoothly over the snow, we shall first understand what are the problems that we face while sliding over snow in the absence of a ski.
We know that snow is made up of salt and ice which in turn is made up of water. Now, ice under normal freezing temperatures forms solid blocks but when mixed with salt, the property of ice to form big solid blocks is lost. This is the reason why snow is soft and its constituent ice particles are very small. Now, when a person walks over this thick layer of snow, then because of the small size of our feet, great pressure is applied on snow and it breaks down to plummet upon itself.
This is where skis come. These are big sheets of metals that distribute the pressure of our weight over a greater region, hence not letting the snow break. This is the main reason skis help a person slide smoothly over snow.

Note: There is a secondary reason too, as to why skis are used. The coefficient of friction of snow is too low, that is, it is almost frictionless. So, the use of skis makes it harder for us to topple on ice as it reduces the combined height of center of mass of ski and person and hence makes it easier to walk and slide.