For otherwise identical ski runs (same skier, same trajectory) made with skis of different surface areas, the acceleration (and hence net force) experienced by each skier will be the same (since the trajectories are identical). Since all the other forces (weight, aerodynamic forces) are the same, the force the skis exert on the skier and the snow must also be the same for the different skis. What is different is the pressure the skis exert on the snow, since the skis of larger area must exert a smaller pressure to give the same total force (and hence will penetrate the snow to a smaller degree...). Drawing the free-body diagram will help elucidate this reasoning by prompting the question of the net force on the skier. I'm sure ruffyryder's physics teacher is proud of him.
The same force.... but on different skis spread over the snow in different amounts of surface area.... If you don't think surface area has any significance in relating to how force is applied think about how differently a 150lb man falls to earth with a open parachute versus a closed one.... What's the difference in how the force effects his impact and why is it different if all the elements are the same except the resistance due to surface area....
.... and penetrating the snow less means less distance for the skier to decellerate, which is a greater application of force per distance traveled..... ergo more force per skier distance traveled..
perhaps I am wrong.... not being an engineer and all....
