Skiing has a lot of physics involved in it. For example, the approximate coefficient of friction for waxed skis on snow is on the front of the reference table. Using the equation Ff=(coefficient of friction)Fn Using this equation, you can find the force of friction. All you need to know is the normal force and the coefficient of friction which is on the front of your reference table. To calculate the normal force you need to multiply the mass of the skier by gravity (9.81m/s^2). After calculating all of that, you'll find the frictional force of the skier.