The Physics of Cross-country Skiing
Cross-country skiers must take certain physics principles into account, including the following:
- Friction - Cross-country skiers have a love-hate relationship with friction -- it's produced when skis make contact with snow, and it can either help or hinder a cross-country skier. When skiing downhill, less friction is better -- the skier can increase speed and distance with less effort. However, when attempting to move along a level plane, especially when trying to make uphill progress, friction is needed so the skis can grip the snow and allow the skier to push off and move the other ski forward.
- Gravity - While gravity pulls us down to the ground, it doesn't necessarily pull us downhill -- it must be overcome through power and momentum so the skier can move forward on a downhill plane. Gravity also allows the cross-country skier to keep his or her balance and remain grounded while skiing uphill.
- Drag - Air molecules surround us, and when we move, those molecules must get out of the way. The rearrangement of these molecules creates drag, or wind resistance, which slows down skiers. You can reduce drag by making yourself smaller by crouching down and using controlled arm and leg motions.
- Force - Force is generated from the cross-country skier's legs and his or her poles, which are used to push and pull the skier forward. The pole's horizontal range of motion affects speed, but vertical motion doesn't.
- Mass - Skiers come in all shapes and sizes, and body mass plays a big part in the physics of cross-country skiing. Larger skiers will encounter more friction between the ski and the ground because of body weight. However, if those skis are waxed, the extra weight can help increase the skier's downhill speed. A smaller frame, on the other hand, will produce less drag and may not be able to reach the same downhill speed.
- Velocity - Velocity in skiing is mostly determined by stride frequency and stride length. The length of the stride has more impact on a skier's speed than the frequency of his or her strides.
So what kind of gear do you need to begin cross-country skiing? Keep reading to find out.