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# How to get low in a turn... - Page 3

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Obviously at the base of the 1/4 pipe you have 1 g on your skis, so the difference (since the g forces from the jump are accelerating you UP while gravity is pulling you DOWN) is close to 2.5g.  Or to put it simply, the difference between -1 and +1.5 is 2.5.

I am not sure I follow you here.  If you exert 1 g downwards then you need slightly more than one g to become airborne.  So 1.5g is 1.5g, you don't add the 1 g from your weight to arrive at the answer.   I think you are confusing definitions, not math.

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Mate, I have a Bachelors degree in Electrical Engineering, so I know a thing or two about maths and physics... or at least I did 20 years ago.  So enough with the patronizing tone...

Obviously at the base of the 1/4 pipe you have 1 g on your skis, so the difference (since the g forces from the jump are accelerating you UP while gravity is pulling you DOWN) is close to 2.5g.  Or to put it simply, the difference between -1 and +1.5 is 2.5.

This is of course a simplification.  Forces are a complex variable (value and a vector) and the arc of the 1/4 pipe will have a changing vector as it arcs up. f(t) or force as a function of time.

However the point remains that in order to become airborne, the vertical component of the force vector has to be > 1g to overcome the force of gravity.

So yes, when you hit a booter or 1/4 pipe, you will briefly experience > 2 g's, assuming you have enough speed to get airborne.

I mean can you honestly tell me you've never experienced the significant g forces when hitting a jump!!??  You don't just magically start floating.

I think he is pointing out that g is used to measure acceleration and you're not accelerated unless you're actually moving in the direction of the force. I.e. force and acceleration are different

in every day parlance, g is also used to describe a mechanical reaction force that produces the feeling of one weight, like fighter pilots pulling up to 8g in certain maneuvers, see the discussion here, on g-force. http://en.wikipedia.org/wiki/G-force

the point being that the jumping up and down does not imply you were pulling 2g - try picking up someone of your own weight on your shoulders, that would be 2g. Now try 2 of them, so there's 3 of you for 3g - again, 3g is technically wrong since you're not accelerated, but I just completely confused myself just typing this...

oh, by the way, after picking up 2 of yourself on your shoulders, now try to do some sideways crunches or squats at 3g, get a feel for what a WC athlete can do... and why analyzing their photos can often be misleading, especially when you relate it to an everyday skier...

p.s. however, i think your math was decent, at least from the perspective of the g being a result of speed and radius. that is correct. however, bending a 21m into a 15m, that's very very good, if true

p.s.2 read this for fun: http://en.wikipedia.org/wiki/Galileo's_Leaning_Tower_of_Pisa_experiment and then watch this for a complete mindfucx http://thekidshouldseethis.com/post/the-hammer-feather-drop-in-the-worlds-biggest-vacuum-chamber

p.s.3 Gravity is not a force but a field: http://en.wikipedia.org/wiki/Gravitational_field

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The gravitational field is a vector field that describes the gravitational force which would be applied on an object in any given point in space, per unit mass. It is actually equal to the gravitational acceleration at that point.

p.s.4 hey, i'm getting good at this...

Edited by razie - 2/3/15 at 5:50am
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Originally Posted by TheRusty

My math skills are a little rusty. Is "2" still greater than "1.54"?

I apologize if the concept of gravity did not seem to be relevant to "g" forces. I thought it might be good to start the discussion at finding out how many meters per second per second 1G was. Let's continue this discussion after you find a scale.

Mate, I have a Bachelors degree in Electrical Engineering, so I know a thing or two about maths and physics... or at least I did 20 years ago.  So enough with the patronizing tone...

Obviously at the base of the 1/4 pipe you have 1 g on your skis, so the difference (since the g forces from the jump are accelerating you UP while gravity is pulling you DOWN) is close to 2.5g.  Or to put it simply, the difference between -1 and +1.5 is 2.5.

This is of course a simplification.  Forces are a complex variable (value and a vector) and the arc of the 1/4 pipe will have a changing vector as it arcs up. f(t) or force as a function of time.

However the point remains that in order to become airborne, the vertical component of the force vector has to be > 1g to overcome the force of gravity.

So yes, when you hit a booter or 1/4 pipe, you will briefly experience > 2 g's, assuming you have enough speed to get airborne.

I mean can you honestly tell me you've never experienced the significant g forces when hitting a jump!!??  You don't just magically start floating.

Ok - no more patronizing. I'm impressed. You win!

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Originally Posted by razie

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Mate, I have a Bachelors degree in Electrical Engineering, so I know a thing or two about maths and physics... or at least I did 20 years ago.  So enough with the patronizing tone...

Obviously at the base of the 1/4 pipe you have 1 g on your skis, so the difference (since the g forces from the jump are accelerating you UP while gravity is pulling you DOWN) is close to 2.5g.  Or to put it simply, the difference between -1 and +1.5 is 2.5.

This is of course a simplification.  Forces are a complex variable (value and a vector) and the arc of the 1/4 pipe will have a changing vector as it arcs up. f(t) or force as a function of time.

However the point remains that in order to become airborne, the vertical component of the force vector has to be > 1g to overcome the force of gravity.

So yes, when you hit a booter or 1/4 pipe, you will briefly experience > 2 g's, assuming you have enough speed to get airborne.

I mean can you honestly tell me you've never experienced the significant g forces when hitting a jump!!??  You don't just magically start floating.

I think he is pointing out that g is used to measure acceleration and you're not accelerated unless you're actually moving in the direction of the force. I.e. force and acceleration are different

in every day parlance, g is also used to describe a mechanical reaction force that produces the feeling of one weight, like fighter pilots pulling up to 8g in certain maneuvers, see the discussion here, on g-force. http://en.wikipedia.org/wiki/G-force

the point being that the jumping up and down does not imply you were pulling 2g - try picking up someone of your own weight on your shoulders, that would be 2g. Now try 2 of them, so there's 3 of you for 3g - again, 3g is technically wrong since you're not accelerated, but I just completely confused myself just typing this...

oh, by the way, after picking up 2 of yourself on your shoulders, now try to do some sideways crunches or squats at 3g, get a feel for what a WC athlete can do... and why analyzing their photos can often be misleading, especially when you relate it to an everyday skier...

p.s. however, i think your math was decent, at least from the perspective of the g being a result of speed and radius. that is correct. however, bending a 21m into a 15m, that's very very good, if true

p.s.2 read this for fun: http://en.wikipedia.org/wiki/Galileo's_Leaning_Tower_of_Pisa_experiment and then watch this for a complete mindfucx http://thekidshouldseethis.com/post/the-hammer-feather-drop-in-the-worlds-biggest-vacuum-chamber

p.s.3 Gravity is not a force but a field: http://en.wikipedia.org/wiki/Gravitational_field

Quote:
The gravitational field is a vector field that describes the gravitational force which would be applied on an object in any given point in space, per unit mass. It is actually equal to the gravitational acceleration at that point.

p.s.4 hey, i'm getting good at this...

Thanks Razie. Do you also find it easier to hop on one leg than to leg press twice your body weight?

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Originally Posted by TheRusty

Thanks Razie. Do you also find it easier to hop on one leg than to leg press twice your body weight?

Interesting... trying to think as to why that is.... lifting one's weight is not an extra g, unless you actually accelerate yourself with 1g, i.e. 9.81 m/s/s so my diff math is completely rusty, but back-of-napkingly i would guess you have to jump like 3m in 1 sec, with what, like a half second impulse? So now we're talking impulse, i.e. force over time...

... which gets us to a very interesting point, because the timing of force application in WC turns is quite short. smooth, but short.

cheers,

raz

Funny - I think the answer could possibly come from consulting ... (wait for it...) ... Kenny G? Otherwise you are getting suspiciously close to showing a hole in Co's logic. You can't do that because I've already declared Co to be the winner.

Quote:
Originally Posted by razie

I think he is pointing out that g is used to measure acceleration and you're not accelerated unless you're actually moving in the direction of the force. I.e. force and acceleration are different

in every day parlance, g is also used to describe a mechanical reaction force that produces the feeling of one weight, like fighter pilots pulling up to 8g in certain maneuvers, see the discussion here, on g-force. http://en.wikipedia.org/wiki/G-force

the point being that the jumping up and down does not imply you were pulling 2g - try picking up someone of your own weight on your shoulders, that would be 2g. Now try 2 of them, so there's 3 of you for 3g - again, 3g is technically wrong since you're not accelerated, but I just completely confused myself just typing this...

oh, by the way, after picking up 2 of yourself on your shoulders, now try to do some sideways crunches or squats at 3g, get a feel for what a WC athlete can do... and why analyzing their photos can often be misleading, especially when you relate it to an everyday skier...

p.s. however, i think your math was decent, at least from the perspective of the g being a result of speed and radius. that is correct. however, bending a 21m into a 15m, that's very very good, if true

p.s.2 read this for fun: http://en.wikipedia.org/wiki/Galileo's_Leaning_Tower_of_Pisa_experiment and then watch this for a complete mindfucx http://thekidshouldseethis.com/post/the-hammer-feather-drop-in-the-worlds-biggest-vacuum-chamber

p.s.3 Gravity is not a force but a field: http://en.wikipedia.org/wiki/Gravitational_field

p.s.4 hey, i'm getting good at this...

Just because you're not accelerating doesn't mean you're not experiencing 1g.  You're forgetting that g-force acceleration is relative to a free-fall.

http://en.wikipedia.org/wiki/G-force

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The g-force acceleration (save for certain electromagnetic force influences) is the cause of an object's acceleration in relation to free-fall.[1][2]

The g-force acceleration experienced by an object is due to the vector sum of all non-gravitational and non-electromagnetic forces acting on an object's freedom to move. In practice, as noted, these are surface-contact forces between objects. Such forces cause stresses and strains on objects, since they must be transmitted from an object surface. Because of these strains, large g-forces may be destructive.

Gravitation acting alone does not produce a g-force, even though g-forces are expressed in multiples of the acceleration of a standard gravity. Thus, the standard gravitational acceleration at the Earth's surface produces g-force only indirectly, as a result of resistance to it by mechanical forces. These mechanical forces actually produce the g-force acceleration on a mass. For example, the 1 g force on an object sitting on the Earth's surface is caused by mechanical force exerted in the upward direction by the ground, keeping the object from going into free-fall. The upward contact-force from the ground ensures that an object at rest on the Earth's surface is accelerating relative to the free-fall condition (Free fall is the path that the object would follow when falling freely toward the Earth's center). Stress inside the object is ensured from the fact that the ground contact forces are transmitted only from the point of contact with the ground.

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If the pilot were suddenly to pull back on the stick and make his plane accelerate upwards at 9.8 m/s2, the total g‑force on his body is 2 g, half of which comes from the seat pushing the pilot to resist gravity, and half from the seat pushing the pilot to cause his upward acceleration

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p.s. however, i think your math was decent, at least from the perspective of the g being a result of speed and radius. that is correct. however, bending a 21m into a 15m, that's very very good, if true

Like I said, I didn't have a 15 meter tape measure on me and It's just a guess.  I was trying to gauge my arcs in the snow (under the lift) relative to a 25meter pool.  15 meter radius is 30 meter's diameter and they sure looked tighter than that to me.

Here's a still from a video from earlier that day.  This turn was only at ~ 20mph.  In the 38mph turn (gps/trace snow) I was way lower and generating significantly more pressure on the outside ski.  It this pic you can see the outside ski bent.  I'm only a beginner skier with 6 days of skiing at the time of the pic.  But to my eye the ski looks pretty curved relative to the unloaded inside ski.  BTW my inside hand was dropped deliberately to touch the snow.

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If the pilot were suddenly to pull back on the stick and make his plane accelerate upwards at 9.8 m/s2, the total g‑force on his body is 2 g, half of which comes from the seat pushing the pilot to resist gravity, and half from the seat pushing the pilot to cause his upward acceleration

that's exactly what i was saying - you need to push yourself up with 9.8 m/s/s to get 2g - which means you jumped up about 3m, i.e. 10ft in the air... i.e. feet on the ceiling... did you do that? Because if not, then it was far less than 2g...

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that looks about nominal, i.e. sidecut. remember that 21m is not what a flat ski can do - a flat ski will just about go straight.... a nominal 21m radius is what you get when you bend the ski at the nominal sidecut... more or less like above.

I can bend a 23m into a 20m, if I am precise and work hard (i.e. not consistently) but I cannot bend it into an 18m. On the other hand, mine is a WC race ski not a consumer ski, so what do I know...

btw - not bad for 6 days on snow. you have good balance and range of motion and doing that is a good idea as it gets you forward, as you can see from the snow spray.

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Originally Posted by razie

that looks about nominal, i.e. sidecut. remember that 21m is not what a flat ski can do - a flat ski will just about go straight.... a nominal 21m radius is what you get when you bend the ski at the nominal sidecut... more or less like above.

I can bend a 23m into a 20m, if I am precise and work hard (i.e. not consistently) but I cannot bend it into an 18m. On the other hand, mine is a WC race ski not a consumer ski, so what do I know...

btw - not bad for 6 days on snow. you have good balance and range of motion and doing that is a good idea as it gets you forward, as you can see from the snow spray.

This is a good discussion and I'm not trying to be argumentative.  I'm really trying to understand what you're saying, because I could have missed something...

So you're saying that if you accelerate up at 9.8m/s^2, then you would hit the roof.  And I agree that would be the case in zero gravity.  But do you agree that we are accelerating down at 9.8m/s^2 just standing up?  Sounds weird since we are stationary, but g forces are measured relative to a free-fall.  So relative to a free fall, we are moving, hence the 1g even though we're not going anywhere.

So even when we jump up at 9.8m/s^2, we're also accelerating down the whole time due to gravity (-1+1=0).  So the net sum of the g forces is 0, but at the take off point in the jump we have gravity (-1) and our acceleration forces from jumping (+1).

For every action, there is an equal and opposite reaction.  So in order to jump up at 1g, we first have to exert that force down through our feet to push off.  Add that force with gravity and we have 2g's on our feet, if only for an instant.

Not sure if I'm explaining any better, or I'm just repeating myself.

Anyway...

Thanks for the encouragement re my pic.  Apparently though, others think I'm totally off balance and a danger to other on the slope (http://www.epicski.com/t/132350/rant-cant-find-runs-to-ski-the-way-i-want-new-skis/30#post_1829441)

Which is weird, because I feel totally in control and balanced.  Which isn't to say I couldn't improve my form, but if I were unbalanced and out of control I would be falling and failing my arms around.  Which I don't so who knows...

I will defer to you on the ski bending as I really know nothing about it. So you're saying I'm basically stuck into ~20 meter radius carve turns on these skis.

I'll let you fgure out the g thing. As long as you agree that carrying another like you is 2g, you can go from there and see if it would feel the same load on the legs just hoping 1mm up from the floor.

On the photo, you seem in balance on a moving ski enough to move that much, that is good for 6 days... I can see you're supporting with the inside ski, you were trying to reach down, but.... I know skiers that ski for years and stil look like that

... It doesnt tell me anything about control though. If you move with a speed that allows you to turn and also stop at will, that is control. Aboutt the 20m radius, carving is not the only way to turn the skis... For beginners, short radius skis are usually very strongly recommended, for good reasons. And I would not carve at speed until I am confident that I can skid around on any radius and also stop at will.

Cheers

P.s. The novelty of the carving thing will wear off quickly.... It is much more fun to be able to do whatever you want all over the mountain!
Edited by razie - 2/3/15 at 4:07pm

Wow.

I can't believe I just read through this whole thread.  It's like a morbid fascination or something.  I think Colorado is my new favorite person to follow.  I just read one of his other posts as well.  Dude, you are a trip :)

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Originally Posted by razie

I'll let you fgure out the g thing. As long as you agree that carrying another like you is 2g, you can go from there and see if it would feel the same load on the legs just hoping 1mm up from the floor.

On the photo, you seem in balance on a moving ski enough to move that much, that is good for 6 days... I can see you're supporting with the inside ski, you were trying to reach down, but.... I know skiers that ski for years and stil look like that

... It doesnt tell me anything about control though. If you move with a speed that allows you to turn and also stop at will, that is control. Aboutt the 20m radius, carving is not the only way to turn the skis... For beginners, short radius skis are usually very strongly recommended, for good reasons. And I would not carve at speed until I am confident that I can skid around on any radius and also stop at will.

Cheers

P.s. The novelty of the carving thing will wear off quickly.... It is much more fun to be able to do whatever you want all over the mountain!

Yep I agree that loading up a barbell with your weight and resting it on your shoulders will feel like a sustained 2 g's.

I can skid turns and hockey stop on a dime.  Also agree that carving at speed without those skills would be irresponsible and probably deadly.

It's weird I know, but I'm just into carving and big fast powder turns. At least that's how it was for me back when I was a snowboarder.  When conditions didn't cooperate, I just went home... and eventually gave it up all together.  Got into bikes instead.

Guess that makes me a very 2D boarder.  Maybe things will be different on skis... they seem a lot more versatile.

When I get some time I will see what more I can find out on the g-force thing.  I must be a geek because I find that stuff interesting    I think think I may be missing something...

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Originally Posted by peterk123

Wow.

I can't believe I just read through this whole thread.  It's like a morbid fascination or something.  I think Colorado is my new favorite person to follow.  I just read one of his other posts as well.  Dude, you are a trip :)

Never a dull moment inside my head lol!

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Just because you're not accelerating doesn't mean you're not experiencing 1g.  You're forgetting that g-force acceleration is relative to a free-fall.

http://en.wikipedia.org/wiki/G-force

Like I said, I didn't have a 15 meter tape measure on me and It's just a guess.  I was trying to gauge my arcs in the snow (under the lift) relative to a 25meter pool.  15 meter radius is 30 meter's diameter and they sure looked tighter than that to me.

Here's a still from a video from earlier that day.  This turn was only at ~ 20mph.  In the 38mph turn (gps/trace snow) I was way lower and generating significantly more pressure on the outside ski.  It this pic you can see the outside ski bent.  I'm only a beginner skier with 6 days of skiing at the time of the pic.  But to my eye the ski looks pretty curved relative to the unloaded inside ski.  BTW my inside hand was dropped deliberately to touch the snow.

Your CoM is very very far behind your feet. You are standing up, but nowhere near functional balance. Form follows function, not visa versa.
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Originally Posted by markojp

Your CoM is very very far behind your feet. You are standing up, but nowhere near functional balance. Form follows function, not visa versa.

My COM is clearly behind my inside (unweighted) foot, but it looks/feels to be forward of my outside (weighted) foot?   But you're saying that's not the case and my COM is behind both feet right?

To correct this I need to do what?  Bring my inside foot back and lean further forward?

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....

What does that stance do for you?  How does it work?  What were you doing different before you discovered doing it this way?

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My COM is clearly behind my inside (unweighted) foot, but it looks/feels to be forward of my outside (weighted) foot?   But you're saying that's not the case and my COM is behind both feet right?

To correct this I need to do what?  Bring my inside foot back and lean further forward?

There are A LOT of issues with your picture. Pick your cure. I'll add more later when im not hitting little buttons on a phone, but to start with, there's an awful lot of body english going into fairly low edge angles. Think about why that is. More later.

Now none of the above is trying to be mean or discouraging. Clearly you desire to ski better. The change will be challenging, but truly great fun! You're clearly very athletic which will pay off in spades when you get down to business sorting things out.
Edited by markojp - 2/3/15 at 10:24pm
Guys and gals, this is his MA thread... (http://www.epicski.com/t/132350/rant-cant-find-runs-to-ski-the-way-i-want-new-skis/30#post_1829441)

He posted that photo here in a discussion on ski bend. He admitted he was reaching down, that inclines him and he's wide, supporting with the inside foot as well and does a lot of stuff. I thought he was balanced decently since he was moving a lot, to try and reach down, for only 6 days on snow with no instruction...

I guess I don't know how a typical 6 days skier would look...
He's fine for a six day skier, just not for a six day skier who wants to hit the land speed record on the slopes.
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Originally Posted by razie

Guys and gals, this is his MA thread... (http://www.epicski.com/t/132350/rant-cant-find-runs-to-ski-the-way-i-want-new-skis/30#post_1829441)

He posted that photo here in a discussion on ski bend. He admitted he was reaching down, that inclines him and he's wide, supporting with the inside foot as well and does a lot of stuff. I thought he was balanced decently since he was moving a lot, to try and reach down, for only 6 days on snow with no instruction...

I guess I don't know how a typical 6 days skier would look...

As noted, he's very athletic which will help steepen the learning curve, but only if he begins to understand what he doesn't.

Thanks to all for the input. I enjoy learning and reading about skiing almost as much as the skiing itself.

Sorry if I come across as stubborn to learn!

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Here's the formula and example on how to calculate the G forces.

(S^2/R)/32=G

S=speed in feet/second

So for my example I was going 38mph (55.73 f/s) into the corner.  Not sure on the radius but it's obvious less than 21meters.  Maybe the ski was bent into 15 meters (49 feet). Reasonable guess?

So doing the math we get 1.9G's for a 15 meter radius and 2.9G's for a 10 meter radius.

IIRC I read that the top GS skiers pull 3-4G.

My jumping up and down example isn't exactly the same as an extended leg in the turn, but was just there to give a ball park for the forces involved.

I can jump up and down on one leg without any trouble, so I don't see a 2-3G turn being a problem.

But I'm just a beginner using physics/logic, rather than experience to draw my conclusions.  I could be way off, but it seems about right...

I find it a lot easier to calculate G forces by the intensity of chill in the spine. At least I believe you will find more G forces in your skiing much faster through the use of this measurement rather than the chalk board in all your head's.

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Originally Posted by Rich666

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that's probably the coolest thing I've seen all week... hop turns :)

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No, those are my carved turns. These are my hop turns:

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