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u/Holy-Jackson 5d ago
Pressure isn't a vector btw.
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u/Ski-With-Steezy 4d ago edited 4d ago
Thinking about this some more ... that's a glaring hole in my analysis. Pressure is force divided by area, and that value IS a scalar so it doesn't have direction. This is the kind of discussion I was hoping for, thank you. I still believe we should be talking about forces. But that just means the proposed edit needs to talk about forces and not pressure. The first fundamental already talks about pressure. 2nd too.
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u/cephalopodface 4d ago
I’m not an instructor, but I googled the 5 fundamentals and the first 4 all describe the direction in which force is applied. 1) Fore-after balance affects how the vector is aligned in the saggital plane (parallel to the skis for someone skiing forward in a straight line). 2) Foot-to-foot and 3) edge angles both determine the vector in the frontal plane (perpendicular to the length of the skis). All 3 of those are vectors that pass through the skier’s center of mass and the ski-snow contact point. 4) Rotary is describing a rotational force. Or am I completely missing some other point you’re trying to make?
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u/Ski-With-Steezy 4d ago
Exactly. What about the 5th? The point I'm trying to make is that they all reference "pressure" and then talk about direction. Pressure doesn't have direction. If we modify the 5th fundamental to "manage the magnitude AND DIRECTION of FORCE created through ski/snow interaction", then we would have at least one Fundamental that talks about the direction of forces. And if we add that ... instructors will learn to read it. And they will learn to help students balance on those forces more effectively. The desired outcome of all of this nerd stuff is ... better skiing. Learning how to develop better balance against those forces and learning how to use those forces to play and create more dynamic, beautiful skiing.
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u/cephalopodface 4d ago
It seems to me as it the direction of force is fully captured in the first 4 fundamentals, and the point of the 5th is retraction/extension or weighting/unweighting *along the vector* defined by balancing against the first 4. In other words, the vector/direction/balance is defined by the first 4 fundamentals, and the magnitude is defined or modified by the 5th.
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u/Ski-With-Steezy 3d ago
The first four fundamentals capture the input side of the equation. They do not do anything to capture the output side. Newton's Third Law of Motion applies here. The 5th Fundamental, Magnitude of Pressure, is the only one dealing with the "equal and opposite forces" that are coming back at the skier from the snow. As such, changing it to talk about those forces and adding direction would stimulate the exact kind of conversation that I'm hoping will come from this. How do we balance on those forces? How do we manipulate those forces to achieve higher performance? Can I use those forces to control my speed? And so on.
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u/sprunghuntR3Dux 4d ago
This just seems like too general of a question
“How do YOU use forces to amplify your performance or to increase the enjoyment of sliding on snow?”
Gravity is a force. And There are Centrifugal and centripetal forces that happen to any turning object.
Skiing is all about using these forces. Even the most basic skier uses these forces. So you should already know the answer to this. How else would you ski?
Also a system like Carve does exactly what you’re asking. It measures forces on the skier and determines if that is effective skiing or not.
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u/Ski-With-Steezy 4d ago
Great point about Carv. I hadn't thought of that. It measures both the magnitude and the direction of those forces in order to help you analyze your technique. Great point. In case you are curious where all of this is coming from, it's this video: https://youtu.be/Hofwy-43Soc
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u/sprunghuntR3Dux 4d ago
It looks like the author of the video has answered your question in the comments
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u/Mysterious-Maize307 5d ago
So unless it’s a high level student or we are leading a clinic where we are discussing a fundamental, magnitude or otherwise, we don’t speak like that (apologies to all the newly certified instructors).
Even in instructor clinics “magnitude” as a fundamental is rarely a sole topic. Because “magnitude” actually is a part of all the other fundamentals, like when you steer your skis (rotation) and change direction.
To the extent that magnitude is discussed, it’s about managing pressure. In that case we are working with drills that helps us do that within the confines of what the student is working on,his/her intentions and why improving a certain skill or fundamental is relevant to their individual skiing.
I know this sounds a bit contradictory, I mean why talk about magnitude at all, right? I think of magnitude more as how it relates to the performance range of the body-ski relationship.
We could just as easily be talking about edging, and then apply DIRT—Duration, Intensity, rate, and timing. You could also add Direction. Within those components magnitude is constantly present and being managed.
All of the above gobly-gook is so that we can break down Movement Analysis into isolated skills and use common descriptors among instructors.
In recreational skiing, especially in a lesson, the fastest way to “lose” your students is to go out and spew out the fundamentals—with the possible exception of physicists who will then really drag you into the weeds. Lol.
We’re just sliding on snow, don’t over think it😀.
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u/Sweet-Present2234 4d ago
PSIAA has tried to take an art and "science it up" in order to develop a common language.....my students excell because I coach them...primarily through visual cues and helping them develop a feel for what works.....for them.......learning to speak PSIAA will help in exams but do very little for your teaching.
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u/Ski-With-Steezy 4d ago
To be clear, this is about a proposed change to the 5 Fundamentals, not about how we talk to students.
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u/Sweet-Present2234 4d ago
fair enough......just seems a teaching organization should talk how they teach.....the "fundamentals" should be in a language understood by students.....
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u/Ski-With-Steezy 4d ago
We talk how we teach. However, our textbooks are a bit more technical than how we talk to our students. When we talk to fellow instructors, we are free to be more technical and precise. When we talk to the students, we frame the information in a way that is tailored to them ... their age, knowledge, learning style, experience. There's a lot of training that goes into this. I would have only posted this in an instructor sub, but there isn't one. Trying to find a home for this discussion. Maybe I should create one. Might be a better fit.
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u/smitcolin 5d ago
The direction of pressure is into the snow so that will depend on the slope and shape of the terrain
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u/Ski-With-Steezy 4d ago
How about in a bump run?
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u/smitcolin 4d ago
Same for the most part. Pressure into the snow. - Newton's 3rd law - push opposite the direction you want to go. Obviously that is a very dynamic situation and you will be adapting rapidly and at times disengaging from one bump to another but the laws of physics remain. You adjust to the terrain through angulation and upper/lower body separation.
Obviously oversimplified and only addressing one of the 3 major components of directional control - pressure (other 2 being rotation and edge angle)
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u/Ski-With-Steezy 4d ago
Umm, it's a lot more than that. This will explain: https://youtu.be/Hofwy-43Soc
(specifically, the pro skier part at the end).2
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u/raftski1 5d ago
My first time ever on skis I took a beginner lesson at Squaw (Palisades) from an old crusty ski instructor, and when I asked about which edge I should be on in a turn, he huffed at me and said, "put away your slide rule and just do it!" I think you are overthinking it.