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# Top of turn speed control

Controlling speed at the top of the turn is a popular and important subject. But what actually causes this speed control??

You can control speed by skidding of course, but you can also control speed in arced turns, even on ice.

One factor that is often overlooked is the deflection of the CoM.

If you are not familiar with collision physics, there are two types of collisions:

- Elastic collision. This is collision without loss of energy, e.g. two steel balls colliding

- non-elastic collisions. This is collision where are least one of the bodies absorbs energy, e.g. a car accident.

In skiing, when the skis are engaged at the top of the turn they can be engaged with an angle to the direction of the CoM.

If this angle is small to moderate the skis don't have to skid if the engagement is delayed until a critical plaform angle is achieved. The turn is arced. It can also be combined with some skidding, but then some of the energy is absorbed by the snow instead of the skier. This can be viewed as a non-elastic collision between the skier and the hill. Energy is absorbed by the skier and/or the snow.

Basically the energy lost is due to that only the velocity component parallel to the ski is maintained.

So the energy after the engagement is:

E=m(v*cos(alpha))^2/2, where m is the mass, v is the velocity before engagement and alpha is the aforementioned angle.

Some simple cases:

alpha=0 degrees means no energy lost.

alpha=45 degrees means half the energy is lost

alpha=90 all energy is lost (an edge locked hockey stop)

now since the energy gained between two turns is equal to m*g*turn length*sin(slope angle)

we can calculate the terminal velociy by equaling the two energy expression, but I won't bother you with the details.

To put it a little less nerdy bend the tips more and sooner going into the turn directing more force to resist your forward momentum; skid it to let the snow do the work.  OR be patient, don't bruise the snow engage cleanly and get lots of tail pressure in the top half of the turn with little pressure at all in the bottom of the turn (with lots of separation) for the opposite effect.

Ghost, It sort of sounds like tail to tip (reverse) pressure migration.. If we rock the tail to accelerate the end of the turn, do we do the opposite to decelerate the turn? Is this what you are saying?

Not sure I follow you, but using that ski tip to push you backwards (with respect to the direction of you COM, which you have directed more uphill from the last turn) asap will slow you down.

Quote:
Originally Posted by Jamt

Controlling speed at the top of the turn is a popular and important subject. But what actually causes this speed control??

You can control speed by skidding of course, but you can also control speed in arced turns, even on ice.

One factor that is often overlooked is the deflection of the CoM.

If you are not familiar with collision physics, there are two types of collisions:

- Elastic collision. This is collision without loss of energy, e.g. two steel balls colliding

- non-elastic collisions. This is collision where are least one of the bodies absorbs energy, e.g. a car accident.

In skiing, when the skis are engaged at the top of the turn they can be engaged with an angle to the direction of the CoM.

If this angle is small to moderate the skis don't have to skid if the engagement is delayed until a critical plaform angle is achieved. The turn is arced. It can also be combined with some skidding, but then some of the energy is absorbed by the snow instead of the skier. This can be viewed as a non-elastic collision between the skier and the hill. Energy is absorbed by the skier and/or the snow.

Basically the energy lost is due to that only the velocity component parallel to the ski is maintained.

So the energy after the engagement is:

E=m(v*cos(alpha))^2/2, where m is the mass, v is the velocity before engagement and alpha is the aforementioned angle.

Some simple cases:

alpha=0 degrees means no energy lost.

alpha=45 degrees means half the energy is lost

alpha=90 all energy is lost (an edge locked hockey stop)

now since the energy gained between two turns is equal to m*g*turn length*sin(slope angle)

we can calculate the terminal velociy by equaling the two energy expression, but I won't bother you with the details.

So I'm thinking the conclusions your are getting regarding speed control at turn initiation are:

1.  Moving the CoM across the skis at initiation, downhillish, at a big angle to the across-the-hill-direction the skis are pointing and moving, would provide the most speed control (because of energy absorbed by snow or skis or body when the skier collides with the hill).

2.  Moving the CoM across the skis at initiation, forwardish along the length of the skis, as they are pointing and moving across the hill, would provide the least speed control (because less energy is absorbed by the snow or skis or body, when the skier collides with the hill).

If I got that right (did I?), then how about this.  In scenario #1, how about speed control differences comparing a skier facing in the direction of the skis at initiation to a skier facing more downhill at initiation?

Edited by LiquidFeet - 10/21/15 at 10:30am

The top 1/3rd of the turn is where the turn radius is set.  Get into a tighter radius turn and you'll have more speed control.  Or whip the skis around sideways to the hill after you're past the fall line and skid for speed control.  I prefer the answer behind door #1.

The top half of a turn is about acceleration. Inhibit it and you accelerate at a slower rate. How you choose to do that is a personal choice. Perhaps lost in this topic is how the last half of the previous turn effects all of this. Finish your turn well across the hill and you slow down significantly. Thus making speed control less of an issue in the new turn. Before anyone mistakes that for saying don't control your speed there that isn't what I am saying, I am saying more often than not if you need to scrub speed early in a turn you forgot to do it through the end of the last turn.

So Jamt I wonder about the question itself. "Controlling" speed can have three different meanings, more acceleration, maintaining current speed, and of course scrubbing speed. Each have a few different options and exploring them would be great.

Accelerating more would depend on which direction we discuss. Forward acceleration is a bit easier to define, we would need to huck part of our body forward. Laterally accelerating moves could include leaning, angulating, etc...

Conserving momentum is a bit trickier, releasing the core midway through a turn and letting Gravity accelerate it downhill often gets classified as conserving momentum but if an acceleration is occurring it only makes sense that it belongs in the seeking acceleration classification. Not inhibiting flow is in my estimation the better litmus test for any conserving momentum actions. Including any angular momentum but again since that needs to be in the opposite direction once the new turn starts an argument can be made that angular momentum needs to be seen as either reducing or increasing angular momentum

Reducing momentum by increasing friction is the most common way to scrub speed. Skidded turns being one such way. Another is to bend the ski into a tight arc which increases pressure between the ski and snow. The next most common way is to turn across the hill, or even up the hill during turn completion. Which circles right back to my original premise about finishing your turn being by and large the most prescribed way to control speed. Slow line fast is a well known thing here at Epic and it speaks volumes about turn finish and how that effects the first half of the next turn.

JAMT brings up a very overlooked concept about speed control from "collision".  I was first introduced to this in Juris Vagners PSIA book from 1995: "The Ski Instructors Guide to the Physics and Biomechanics of skiing".   This is a free download on some PSIA division websites, look around.

What is the collision effect?  the collision effect is as JAMT described.  you run into something, it pushes back.  That external reactionary force can slow you all the way to a stop if it pushes back enough.  When you run into a wall, the wall pushes back exactly 180 degrees the direction you are going and slows you to a stop, very quickly.  If you were to run into a wall at an angle, it would not slow you quite as much because the reactionary force would not be 180 degrees to the direction you are moving, so it would slow you down some, but it would also deflect you to the side a certain amount.

In skiing think of a hockey slide vs a hockey stop.  In a hockey stop we maximize the edge angle so that we can slow down faster and stop sooner. This actually minimizes the skidding.  a hockey slide we allow the edges to be a little flatter, they skid more..and we slow down less.

So..  as you can see...in a hockey stop vs hockey slide...  the skis pointed 90 degrees to the direction we are traveling, provides a perfect pushback reactionary force that is 180 degrees from the direction we are traveling.  And less skidding=more slowing.  Its the collision itself that mostly causes us to slow down..not the skidding.  There can be some transfer of heat, etc.. in skidding, but generally this is extremely minimal compared to the collision effect.  The collision effect provides an external force to decelerate us.  Literally, brakes.

Now what about ski turns?  Well its similar in a ski turn except the skis are not positioned 90 degrees from the direction we're traveling.  We have much less steering angle then that.  So the reactionary force does not go back exactly 180 degrees from the direction of travel, and the speed bleed is less...but still there is some collision speed bleed that can occur.  Again..higher edges will maximize this effect, flatter skis will cause more skidding and will minimize this effect.

It starts to get murkier there because about now everyone is thinking "but wait, when I carve I go fast, when I skid I go slow.  What gives?"

The thing is, the way a ski is designed with a side cut, when you have a little bit of steering angle on a carving ski, it is able to  deflect the energy to the side very efficiently and minimize speed bleed from the reactionary collision.  The external force vector reacting from the snow is closer to 90 degrees, rather than pointing 180 degrees to the direction we're sliding.  Thus the reactionary forces while carving deflect us on an efficient curved path.  There is a little bit of speed bleed with that too, but not a lot.  As you start ramping up the steering angle, the speed bleed starts to happen because the reactionary force will be pointing more rearwards from the direction of travel.  So it becomes more of a decelerating force.  That's one reason why when you get on the shovels a lot, you will slow down.  More collision pointing more backwards, more deceleration, more speed bleed.  When you get on the tails as much as you can, the collisions are minimized and so is speed bleed...in other words...work the tails to go faster...

When you get even more steering angle that the ski stops carving and starts to skid...that is when we really slow down, but this is the important point:  the speed bleed there is not from the skidding itself, its rather from the larger steering angle which is creating reactionary forces that point more backwards to the direction we are sliding and thus have a greater slowing effect.  And in fact, the higher edge angles you can maintain with the high steering angle is how you will maximize speed bleed.  Make the ski flatter and it skids more and has less collision effect and less speed bleed.  More skidding will become more like a hockey slide instead of a  hockey stop.

So...high-c, how does edge engagement help control our speed?  Well...as i just described, flat skis don't control your speed.  Edged skis do.  Edged skis with enough steering angle to get the collision effect slowing you instead of carving you.    High-C edge engagement will absolutely add speed control through collisionary speed bleed.

Edited by borntoski683 - 10/21/15 at 1:57pm
Quote:
Originally Posted by LiquidFeet

So I'm thinking the conclusions your are getting regarding speed control at turn initiation are:

1.  Moving the CoM across the skis at initiation, downhillish, at a big angle to the across-the-hill-direction the skis are pointing and moving, would provide the most speed control (because of energy absorbed by snow or skis or body when the skier collides with the hill).

2.  Moving the CoM across the skis at initiation, forwardish along the length of the skis, as they are pointing and moving across the hill, would provide the least speed control (because less energy is absorbed by the snow or skis or body, when the skier collides with the hill).

If I got that right (did I?), then how about this.  In scenario #1, how about speed control differences comparing a skier facing in the direction of the skis at initiation to a skier facing more downhill at initiation?

I'm not sure I'm following you exactly here about how the CoM moving across will effect the speed bleed.  But if you get higher edge angles then you have the potential for more speed bleed.....IF you maximize steering angle at the same time.

So how do you maximize steering angle while also maximizing edge angle at the same time?

Quote:
Originally Posted by borntoski683

Quote:
Originally Posted by LiquidFeet

So I'm thinking the conclusions your are getting regarding speed control at turn initiation are:

1.  Moving the CoM across the skis at initiation, downhillish, at a big angle to the across-the-hill-direction the skis are pointing and moving, would provide the most speed control (because of energy absorbed by snow or skis or body when the skier collides with the hill).

2.  Moving the CoM across the skis at initiation, forwardish along the length of the skis, as they are pointing and moving across the hill, would provide the least speed control (because less energy is absorbed by the snow or skis or body, when the skier collides with the hill).

If I got that right (did I?), then how about this.  In scenario #1, how about speed control differences comparing a skier facing in the direction of the skis at initiation to a skier facing more downhill at initiation?

I'm not sure I'm following you exactly here about how the CoM moving across will effect the speed bleed. I thought that was what Jamt was talking about in that first post.  You read it; elastic and non-elastic collisions lead to different amounts of energy "lost."  But if you get higher edge angles then you have the potential for more speed bleed.....IF you maximize steering angle at the same time.  I think you are changing the subject from what Jamt posted last night, but he's the physicist and I certainly may be reading him wrong.

So how do you maximize steering angle while also maximizing edge angle at the same time?  Maximize steering angle?  That depends on where and how fast you want to go.  Maximize edge angle for what purpose, shortening the radius?  I guess I'm not sure what you are getting at.  And I may not be sure what Jamt is getting at either.

He's playing with us, dontchathink?

oh well I thought I was agree with JAMT, but maybe I'm disagreeing, I don't know...I don't think I'm changing the subject.   He specifically mentioned "collisions" and that is exactly what I'm talking about.  Its possible you don't understand me yet.

Quote:
Originally Posted by LiquidFeet

Maximize edge angle for what purpose, shortening the radius?  I guess I'm not sure what you are getting at.

Read my post again.  let's take it  one step at a time.  No, for this discussion, raising the edge angle has nothing to do with the radius of turn, though that will possibly be an outcome also.

So one step at a time...

Why would you maximize your edge angle while trying to hockey stop quickly?

Quote:
Originally Posted by borntoski683

I'm not sure I'm following you exactly here about how the CoM moving across will effect the speed bleed.  But if you get higher edge angles then you have the potential for more speed bleed.....IF you maximize steering angle at the same time.

So how do you maximize steering angle while also maximizing edge angle at the same time?

As I understand it, higher edge angles are more for carving than skidding (high steering angle) and lower edge angles are more for higher steering angles (skidding) than carving.

Or, is the steering angle not comprised of ski direction vs CoM direction and sometimes also referred to as skid angle?

Otherwise a high steering angle with a high edge angle is not just bleeding speed, it is a hockey stop.

Quote:
Originally Posted by Ghost

Not sure I follow you, but using that ski tip to push you backwards (with respect to the direction of you COM, which you have directed more uphill from the last turn) asap will slow you down.

Well, you write "lots of tail pressure in the top half of the turn". Which, to me, sounds like you are recommending starting the turn aft in order to accomplish that. That makes no sense to me at all. Carving turns from the tail to the tip is simply ass backwards. Is it not?

Top half, not top 1/4.   Allow pressure to progressively increase from initiation and max out at apex while moving pressure gradually to the tails from the tips.  If you get all or most of your impulse and change of direction done by mid turn you can release you CM at or near the apex and maximize both your speed and your down hill velocity.

Quote:
Originally Posted by justanotherskipro

Which circles right back to my original premise about finishing your turn being by and large the most prescribed way to control speed. Slow line fast is a well known thing here at Epic and it speaks volumes about turn finish and how that effects the first half of the next turn.

Hi JASP,

From my perspective, I don’t see where your “original premise” is at odds with JAMT’s post. Might say you’re completion of the turn is a continuation of “the deflection of the COM” proposed. And the “slow line fast” is about skiing that slow enough line as fast as you can! Or put another way, to exit this turn with as much energy as you can to pour into the next …or set up the maximum collision at the top of the turn.

I’ve often noted that most skiers are concerned with regulating their speed of descent down the slope. On the other hand, good skiers are less concerned with this and devote more energy to where they are going and GOing there with purpose and drive. While they are likely less concerned about the overall speed because of their greater skill and are often seeking more speed; I also believe they have found and are using the deflection/collision JAMT is speaking of.

Certainly “as fast as you can” will very and the energy carried into the next turn will vary. Colliding with gravity is also a great tactic to combine (for the slow enough line), but still while GOing as fast as you can into it. Ultimately, though, you end up with the top of the next turn starting while you are headed uphill when you really complete those turns, so you are in effect combining JAMTs collision along with your collision with gravity

Nights are getting colder …won’t be long now till we can experiment with this!

Best,

Chris
Quote:
Originally Posted by Rich666

As I understand it, higher edge angles are more for carving than skidding (high steering angle) and lower edge angles are more for higher steering angles (skidding) than carving.

Or, is the steering angle not comprised of ski direction vs CoM direction and sometimes also referred to as skid angle?

Otherwise a high steering angle with a high edge angle is not just bleeding speed, it is a hockey stop.

Higher edge angles have the power to create more snow reaction forces.  If high edge angles are combined with higher steering angles, then you have more speed bleed.  At the furthest extreme that means a hockey stop, but there are shades of grey in between Rich666.

High edge angle does not necessarily mean carving.  Carving requires lower steering angles.  Higher steering angles does not, however, require low edge angles.

The collision factor is how you control speed.  That is why a so called brushed carve can slow you down in high-C.

by the way, I do not particularly think the snow is very elastic.  Its about as elastic as the ground is when you jump off a raise platform to land on the ground.  The ground stops you by pushing back up and decelerates your motion.  The same thing happens when your momentum is blocked by an edged ski.

Quote:
Originally Posted by LiquidFeet

So I'm thinking the conclusions your are getting regarding speed control at turn initiation are:

1.  Moving the CoM across the skis at initiation, downhillish, at a big angle to the across-the-hill-direction the skis are pointing and moving, would provide the most speed control (because of energy absorbed by snow or skis or body when the skier collides with the hill).

2.  Moving the CoM across the skis at initiation, forwardish along the length of the skis, as they are pointing and moving across the hill, would provide the least speed control (because less energy is absorbed by the snow or skis or body, when the skier collides with the hill).

If I got that right (did I?), then how about this.  In scenario #1, how about speed control differences comparing a skier facing in the direction of the skis at initiation to a skier facing more downhill at initiation?

It does'nt really matter how you bring the CoM across, the only difference in this context is the difference in angle between CoM travel direction and the skis.

That said, a highly anticipated/counteracted finish with deep retraction allows you to get a lot more deflection in a natural way.

Quote:
Originally Posted by justanotherskipro

The top half of a turn is about acceleration. Inhibit it and you accelerate at a slower rate. How you choose to do that is a personal choice. Perhaps lost in this topic is how the last half of the previous turn effects all of this. Finish your turn well across the hill and you slow down significantly. Thus making speed control less of an issue in the new turn. Before anyone mistakes that for saying don't control your speed there that isn't what I am saying, I am saying more often than not if you need to scrub speed early in a turn you forgot to do it through the end of the last turn.

So Jamt I wonder about the question itself. "Controlling" speed can have three different meanings, more acceleration, maintaining current speed, and of course scrubbing speed. Each have a few different options and exploring them would be great.

Accelerating more would depend on which direction we discuss. Forward acceleration is a bit easier to define, we would need to huck part of our body forward. Laterally accelerating moves could include leaning, angulating, etc...

Conserving momentum is a bit trickier, releasing the core midway through a turn and letting Gravity accelerate it downhill often gets classified as conserving momentum but if an acceleration is occurring it only makes sense that it belongs in the seeking acceleration classification. Not inhibiting flow is in my estimation the better litmus test for any conserving momentum actions. Including any angular momentum but again since that needs to be in the opposite direction once the new turn starts an argument can be made that angular momentum needs to be seen as either reducing or increasing angular momentum

Reducing momentum by increasing friction is the most common way to scrub speed. Skidded turns being one such way. Another is to bend the ski into a tight arc which increases pressure between the ski and snow. The next most common way is to turn across the hill, or even up the hill during turn completion. Which circles right back to my original premise about finishing your turn being by and large the most prescribed way to control speed. Slow line fast is a well known thing here at Epic and it speaks volumes about turn finish and how that effects the first half of the next turn.

Indeed, and I think this is the source of a lot of disagreements in technical discussions, for example some bump thread train wrecks.

The thing is that conservation of momentum holds for the system, and the system includes snow and the earth and in addition the velocities are vectors.

For example if I fall and come to a complete stop the momentum is conserved, but it doesn't really mean anything.

Quote:
Originally Posted by cgeib

Hi JASP,

From my perspective, I don’t see where your “original premise” is at odds with JAMT’s post. Might say you’re completion of the turn is a continuation of “the deflection of the COM” proposed. And the “slow line fast” is about skiing that slow enough line as fast as you can! Or put another way, to exit this turn with as much energy as you can to pour into the next …or set up the maximum collision at the top of the turn.

I’ve often noted that most skiers are concerned with regulating their speed of descent down the slope. On the other hand, good skiers are less concerned with this and devote more energy to where they are going and GOing there with purpose and drive. While they are likely less concerned about the overall speed because of their greater skill and are often seeking more speed; I also believe they have found and are using the deflection/collision JAMT is speaking of.

Certainly “as fast as you can” will very and the energy carried into the next turn will vary. Colliding with gravity is also a great tactic to combine (for the slow enough line), but still while GOing as fast as you can into it. Ultimately, though, you end up with the top of the next turn starting while you are headed uphill when you really complete those turns, so you are in effect combining JAMTs collision along with your collision with gravity

Nights are getting colder …won’t be long now till we can experiment with this!

Best,

Chris

Yes, and I think one point is that if you don't finish your turns there is less opportunity to have a "collision" at the top of the next one.

Say for instance that you engage you edges when they are pointing down the fall line. If the CoM isn't traveling across the fall-line the slowing effect will be minimal.

In lesser skilled skiers you see this all the time, the CoM is more or less traveling straight down and only the legs move from side to side.

Quote:
Originally Posted by Ghost

Not sure I follow you, but using that ski tip to push you backwards (with respect to the direction of you COM, which you have directed more uphill from the last turn) asap will slow you down.

I thought I said that earlier.

Yes, during the last third of the turn (measured from transition to transition), you can keep your COM accelerating around and even up, or you can release it early.  With regards to the collision or divergence between current momentum and ski direction, there are limits in how much separation you can handle, especially while still allowing engagement of new edges.

Another way to loose speed at the top of the turn is to make sure the edges engage properly and setup high angles so that you can "collide" later, with more force and energy loosage :) grinding the top of the turn doesn't seem to dissipate as much energy as later...?

just saying...

Here's the thing though. I think we agree the vast majority of motive firce is from Gravity and it never sleeps. Turning towards where it is pulling us will reduce our resistance to it. So we accelerate until we reach the fall li
Quote:
Originally Posted by razie

Another way to loose speed at the top of the turn is to make sure the edges engage properly and setup high angles so that you can "collide" later, with more force and energy loosage :) grinding the top of the turn doesn't seem to dissipate as much energy as later...?

just saying...

It can seem that way, but actually no, the dissipation of energy from this has the same potential in all phases of the turn.  You can bleed speed just as much at the top of the turn as you can at the bottom.  The mechanisms are exactly the same.   the difference between the top and the bottom is about the direction of gravity and whether you are turning INTO gravity or AWAY from it.

Bleeding speed in the top half of the turn from this is NOT a futile effort.  And actually, when speed control and smoothness is the goal (as opposed to winning a race), then the top half of the turn is actually where you need to focus your collisionary speed bleeding efforts the most!!!

In the top half you are turning into gravity. If you do that with minimal collisionary speed bleed, then gravity will accelerate you to the greatest extent possible.  that would be for example, when you arc into the fall line or pivot into the fall line.  In those cases you are basically allowing gravity to accelerate you mostly unimpeded.   When speed control is desired, that will result in Z turns with heavy braking in the lower half of the turn.

Or conversely if you use brushing to create more collisionary speed bleed in the top half, then yes gravity is still trying to accelerate you and yes you're turning into gravity just like in all other turns, but you're also applying the brakes the whole time which helps to create less net acceleration through high-C

So, its not a given that net acceleration will be more than zero in the top half.  You can mitigate a considerable amount of it with brushing..which is all about this collisionary effect.

Its very well possible to make ski turns where the resulting speed from top to bottom of the turn remains fairly constant...even though you're turning into and away from gravity during different phases.  This is by working the top half of the turn to use the collisionary deceleration effects as much as you can in order to result in 0 net acceleration as you turn into and through the fall line.  And then after the fall line as you turn away from gravity, you gradually lesson the collisionary effect..ie.....you release.

Working the top half smooths everything out and frees up the skier to focus on releasing activity in the lower half rather then braking z-like activity.

Quote:
Originally Posted by borntoski683

It can seem that way, but actually no, the dissipation of energy from this has the same potential in all phases of the turn.  You can bleed speed just as much at the top of the turn as you can at the bottom.  The mechanisms are exactly the same.   the difference between the top and the bottom is about the direction of gravity and whether you are turning INTO gravity or AWAY from it.

hmm I don't know - at the top, the "collision" pushes my body away from the skis, into gravity, accelerating down the hill: it cannot be maintained. At the bottom, gravity keeps pushing my body into the collision...?

Anyways - I like the concept: slowing down with "collision"... where did I hear that before... trying to remember...

Razie, you're still not understanding what the collision effect is.  Re read JAMT's original post.  Energy is absorbed into the ground.  When we carve we minimize that and deflect as much as possible.  When we create high levels of collsionary force...similar to a car running into a wall...we slow down.

The snow reaction force may or may not contribute decelerating force, depending on your steering angle and edge engagement.  The net result is the acceleration of gravity minus any acceleration in the opposite direction by snow reaction.

If your edges are not engaged, as in you're pivoting, then net acceleration will be pretty close to whatever gravity is.

If your edges are engaged, then it depends on how much they are engaged and what the steering angle is.  If there is less steering angle, like you're arcing, then there will be very little speed bleed and gravity will accelerate you freely as you turn into it, and indeed even the snow reaction force that way can contribute to the same direction as gravity!

However when you are not arcing then you are providing external forces which work against the speed you're carrying.  The snow begins to absorb a lot of your energy the way a wall absorbs the impact of a car into it.

Can you do a hockey stop while skiing up an incline?

Quote:
Originally Posted by razie

Another way to loose speed at the top of the turn is to make sure the edges engage properly and setup high angles so that you can "collide" later, with more force and energy loosage  grinding the top of the turn doesn't seem to dissipate as much energy as later...?

Razie,
In terms of speed control at the top of a turn vs the bottom, I tend to think this is a dynamic where an ounce of prevention equals a pound of cure.
[/quote
Quote:
Originally Posted by Rich666

Razie,
In terms of speed control at the top of a turn vs the bottom, I tend to think this is a dynamic where an ounce of prevention equals a pound of cure.

he he - good one.

Anyways, I like BTS's "collisionary speed bleed" HOOAAH - I like that.

Of course, thinking arc'd, the more you "speed bleed" at the top, the more pressure you invite or rather create, right? I mean E is still mc2, right? ... or thereabouts... give or take a Ricci tensor

Arc'd turns have very little speed bleed, but even they can have a little bit.

Quote:
Originally Posted by Jamt

E=m(v*cos(alpha))^2/2, where m is the mass, v is the velocity before engagement and alpha is the aforementioned angle.

For a second there I thought you're contradicting Einstein, but maybe not... It would be really cool if someone (I could hazard a guess) could calculate the most optimal application point of pressure, to have the best energy expenditure to the exit of the turn... eh?

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