Originally Posted by borntoski683
Once he transfers weight to that new ski, do you think its possible for him to push his new outside ski away from himself? you say its not possible. I say otherwise.
BTS, there may have been some confusion about which ski we’re discussing, the old outside ski or the new outside ski. So, this leaves more that hasn’t been discussed, and I should respond. I thought you’ve been referring to the old outside ski, because I considered that you were aware of the balance issues with pushing off the new outside ski. Up to this point, I’ve been considering all the ways that the ski can rotate while staying balanced. You can push out the outside ski that you are standing on and if the front has more grip than the back, the ski will rotate, but when it’s your only leverage point and you have no lateral momentum or force toward that ski, you will fall over. The only way to keep from falling over is if the ski curves around fast enough to allow centrifugal forces to build to catch you. A carved turn may be predictable enough to rely on the ski turning itself, but not a rotary turn. If he tries to push out that outside ski and the tail catches on a clump of crud, the ski will not rotate predictably and it will not be able to come around to catch him and he will fall over. Or let’s say it’s very icy and he just loses grip everywhere on the ski when pushing it out, it won’t rotate and he will fall. If you are balanced you can deal with this surface variation by making adjustments. Leg rotary allows the ski to rotate faster than the turning radius of the ski while maintaining balance.
Perhaps your questions about reactionary force are demonstrating the thing you are missing with this. The reactionary force on the ground is not what is accelerating the skier down the slope. It’s all about energy. All the energy is coming from the gravitational field. The reactionary force is perpendicular to the direction of travel. The reactionary force does not contribute a single drop of energy to accelerate the person down the slope. All the reactionary force does is cancel gravitational force pointing perpendicular to the ground, so that only the component of gravity pointing down the slope remains. Gravity is the only thing pulling you down the slope. The snow can not provide a reactionary force to rotate the ski all by itself. All it does is prevent movement on one end, and it’s energy from another force that provides the energy to rotate. Where does that energy come from? Here are some possibilities.
1. Gravity. Nope, above fall line.
2. Centrifugal force. Nope, none at turn transition.
3. Inertia from lateral momentum from pushing off the old outside ski. Nope, video shows momentum going the opposite direction.
4. Forward momentum converted to lateral momentum by placing the ski at an angle. Nope, still shot progression shows weight on ski going straight not being placed at an angle.
5. Lateral force exerted by leg. Nope, can’t maintain balance.
6. Rotary force from rolling the knee. Yup, we see the knee roll. Many mogul skiers know to roll the knee to rotate the ski and do it on purpose. Rolling the knee provides the right pressure and rotational force to reliably rotate the ski faster than the turning radius to stay balanced.