Thursday, September 29, 2011

Freestyle Snowboarding—Physics at Play

            “You have to commit. Keep your speed up. Start to twist before you leave the ground; if you don’t you’re not going to make it.” My coach’s words played over and over as I slide away from him and began moving down the mountain. The jump was in front of me; I tried to listen to my coach’s advice, but I couldn’t subside the fear that was building inside me. The closer I came to lip of the jump, the more I doubted my coach, the less committed I became. I thought he just wanted me to ‘go big’. I thought he was being reckless. I thought I knew better… I was wrong.
            I didn’t commit. I didn’t keep my speed up. I didn’t start to twist before I left the ground. The advice my coach gave me that I labeled reckless was really just physics. From the time I began to slide away from him, I was converting potential energy to kinetic energy—kinetic energy that could have been conserved while I was in the air over the jump—kinetic energy that would have helped me clear the jump. The conservation of angular momentum was the physics behind the need for pre-jump twist. Without initial rotation, there was no angular momentum to let me finish my spin.
            Physics are the guiding principles behind all aspects of snowboarding, and whether conscious of it or not, knowing how to snowboard requires a knowledge of physics. As already mentioned, the conversion of potential energy to kinetic energy allows for movement down the mountain (with consideration given to components based on the steepness of the trail). Friction of the snow or ice, the particular base of the snowboard, the wax applied to the base, etc. all play a part in determining acceleration down the mountain. Friction also is a big factor in the park; rails and boxes have varying coefficients of friction. Approaching a rail, your board is interacting with the snow and that’s what dictates the force of friction in the opposite direction of your movement. This changes quickly when you move from snow to the metal or plastic of rails and boxes. Not only does this require an adjustment to your center of gravity and balance, but also the change in the coefficient of friction can either increase or decrease your acceleration, sometimes very abruptly.
            Though my coach’s words of wisdom seemed counterintuitive at the time, physics explains his reasoning; I accused him of being reckless, but without following his advice it was physically impossible for me to clear the jump and finish my rotation. - post written by Kate Homan.

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