A few interesting side tangents came out of another active thread, but it was getting hard to keep all the conversations straight, so I thought I would start a new thread here.
This comment was presented which I found very interesting.
Physics and skiing is one of my favorite subjects. I have a PhD in physics and I have applied it in my coaching for some years. It's just that most force pictures etc just show a moment in time, whereas a full state needs to take derivatives, second derivatives etc of many variables into account. Snow characteristics, skis characteristics, friction etc also play into the picture. Its too complex to get a full picture.
Is it true? Sure.
But, do we need to go into this level of detail to understand skiing? Is there value in going into this level of detail? I would argue "no".
The purpose of applying physics to skiing, as well as biomechanics is to develop generic models that can be used by others to evaluate, coach and develop skiers as well as thier own understanding.
For example, ILS is a cornerstone of modern technique. Its stablising effects on the upper body easily explained by physics. As a simple model, it is a powerful tool to develop skiers, do they use ILS in every turn? Yes/No. Yes...good, No...bad.
When evaluating skiing, we only need to be able to qualify what is happening...there is no value in quantifying it.
Again for example, we may see on video that this one guy, started to rotate one leg, 32/100 of a second before the other leg, then increased the rotation of the second leg by 4.5% to make it up, causing......say a 1 degree off axis rotation of his upper body in that one turn...what is the value of this quantification? .....none that I can see.
In real world coaching we only need to know the goals, and know the problems caused by not achieving those goals.
Want to be a great coach? Learn the basic models, they will take you a very long way.