The two forces acting on a skier are air resistence and gravity. Gravitational force on an inclined plane is directed toward the center of Earth. A racer who can determine his velocity is able to compare the velocity of his competitors and his past records.
Terminal velocity is when the force of gravity equals the drag force, also known as air resistence.
When this occurs, the skier has a constant velocity. In skiing, this is known as the fall line. When someone skis down the fall line, it is called schuassing. Vectors are line segments drawn to represent both the magnitude and the direction of the quantity. You can add vectors by placing the head of one of the vectors to the tail of another vector.