Wednesday, November 9, 2011

Physics of Downhill Skiing

Downhill skiing encompasses many of the physics concepts we have gone over this year, as well as some we have yet to see. I will briefly go over some of the more basic aspects of skiing and turning in a race setting.

What a skier does is turn gravitational potential energy (mgy) into kinetic energy (1/2mv2) by way of motion. Regardless of the trail condition, a ski slope is never frictionless, and with speeds in excess of 80mph air resistance plays a large role as well. The two forces previously mentioned, friction and air resistance, need to be minimized during a race in order for the skier to maximize their kinetic energy in the form of downhill motion.
Air resistance, or drag is minimized mostly in two ways: by a skiers form, and by choice of clothing.
First, the tight clothing that the racer wears is unfortunately not for style, but rather to create less drag (air resistance). Secondly, the body positioning of the skier is designed to decrease body area in the direction of the drag force in order to decrease its effect.

This is the equation for drag force,
C= drag coefficient
P=density of air
A= frontal area of the skier
V= velocity

As C and p are constant, the only component of this equation up to the skier to control is the frontal area. By crouching down, and keeping ones arms and legs close to the body, a skier is able to lower the frontal area exposed to the drag force.

Friction is combated by getting ones skis on edge, to avoid pushing the snow and creating friction force.
Compare:
By getting on edge (and waxing/sharpening your skis) you reduce friction with the snow and allow you to maintain a greater velocity through a turn.

Video of downhill skiing

Website used:
Post written by Corey Resnick