I rather like these explorations and find it disheartening when people make bold statements on 'How it Is' and then dissuade others from continuing the discussion by saying, "It's too complicated and we don't need to know that Stuff to ski anyway
It's true that this subject gets hacked up quite a lot ...but so what? It's always nice to dig a little deeper. Also, some of these participants are new here and my not have read similar threads. Why not indulge us? If someone doesn't want to talk about a subject, they can just move on.
I think you've got it figured out pretty clearly, though a few housekeeping details are in order for the points BTS objected to.
Originally Posted by SteveE
This force is the uphill force someone mentioned, I think, although it is only uphill if your skies are perpendicular to the fall line.
When a ski is perpendicular (and flat) to the slope during transition it's likely going straight
(for a brief moment) while 'flat' to the snow (generally speaking). At this point neither edge
is engaged so no Centripetal Force would be produced by ski/snow interaction. Once that ski is tipped up even a fraction of a degree, it's another story, so if you had added "... and the ski is being deflected downshill..." to your statement above, I think it works just fine.
Originally Posted by SteveE
When we start a carve we have to apply a force to change the direction our mass going in.
This is true in a general
sense as some
force is required to change the direction of a skier, be it gravity, leg-length changes, the wind, etc. so I've no idea why BTS objects to it.
Centripetal Force at the top of a turn (again, generally
speaking) is normally small and overwhelmed by Gravity so we don't notice it but it's there the moment the ski starts to drive any kind of turn via ski/snow interaction.
As to the discussion on things in Orbit or on Ballistic Paths the use of Centrifugal/Centripetal Force depends on your Frame of Reference and what you're trying to analyze. I've found numerous articles that utterly decry any use of CF in describing 'orbit' and others that make a good case for describing it in those terms. Even Wernher von Braun often described it in those terms. (Here is a page
that decries him for it, though this page also presents some good descriptions on Frames of Reference).
A different point of view is seen here
, along with some of the historical thinking on it.Resultant
Force is important in determining final outputs but understanding the component inputs is pretty important too. In the end, the Centripetal Acceleration
generated by a ski is determined by speed
of turn alone, regardless which phase of the turn we are in and regardless of slope angle. Centrifugal Force
takes the prior two items and adds Mass
to the equation - which invites a bit of interference by Gravity.
To be fair, it's pretty hard to get any Centripetal Force from a ski perpendicular to a 95-degree slope...