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One of the sports I like to do during the winter is skiing. When referring to physics, I can think about a lot of relationships comparing both. When skiing down an declined mountain, I know that mg or the weight of gravity is acting on me, as well as the the normal force of the mountain pushing up on me in a perpendicular direction to the mountain. Also, there's a force of friction pushing back me, but not much since I'm accelerating down the mountain. Overall, there's many examples of how newton's laws and/or physics applies to skiing.

So the other day I was skiing along on one of those straight, flat trails so I was naturally a little bit bored. So I decided to see how high I could jump. I pushed off the ground pretty hard and... got like 2 inches of air. I was pretty disappointed in myself so I tried again. This time a squatted down and pushed off the ground with as much force as my skinny legs could muster and... 2.5 inches. Whats wrong with me? So I stopped and tried to jump vertically while not moving and I got much higher (although it was still pretty embargoing). I stood there for a minute and tried to figure out what was going on. Why can I jump higher while standing still than while moving? Eventually I hypothesized that while standing still the vector of the downward force created to make the jump is directed normal to the ground, maximizing the reaction from the ground; however if you try to jump while sliding across the snow on your skis some of the force is applied parallel to the ground due to your forward motion, in effect creating the same magnitude of the resultant force vector but at an angle which trades some vertical height for horizontal distance. Or maybe I'm just really bad at jumping...

'Twas only yesterday that I took my inaugural ski run, traversing the trails of Bristol, and as I cruised down the mountain I began to reflect on the nature of skiing, particularly waxing. My skis weren't particularly well waxed for the day, so I wasn't going quite to fast, but I did have experience waxing skis beforehand (mostly with nordic skiing - for that it was a weekly affair). When one considers the purpose of wax, it's natural to assume that all it does is make the ski smoother, filling in the tiny holes of the ski so that there is less (dry) friction involved. However, while that is part of what makes a certain type of wax good, a bigger influence is the creation of a thin layer of water underneath the skis caused by contact with the snow. This thin liquid layer allows an even lower coefficient of friction to be achieved, and has to be taken into consideration when waxing your skis (or snowboard). Ideally, only a very thin layer of water is created, because too much will create suction due to the fluid nature of the water, while too little will mean there is still too much dry friction. So the relative propensity of the snow to turn into water on contact has to be taken into account in order to create this balance, and this relative propensity is determined largely by temperature, which is why different conditions require different waxes. Colder temperatures make it harder to create a liquid layer, meaning a stiffer, harder wax is needed, because a harder wax will melt more of the contact layer. On the other hand, warmer temperatures work best with a softer wax. For competitive racers, this means that wax is often reapplied before every race in order to get the optimal conditions. However, for the less enthusiastic, a mid-range wax will often work fine. In case you're every feeling slow on the slopes, take this waxing knowledge into consideration. Soon you'll be zipping around like no one's business.