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My size and My speed - Page 2

post #31 of 58
You guys are really good. I wish I could ski slower. Who wants to ski faster? You can already go insanely fast it seems to me...

Pete
post #32 of 58

Physics of Speed

Now that we have established that waxing is not the issue, we can add a little further analysis.

From a physics standpoint, skiing is like controlled falling (that's why they call it a "fall line"). And we all know since Galileo that mass has no effect on terminal velocity (recall his famous experiment with the leaning tower?). So the fact that your husband has more mass or weighs more does not mean that he should be faster than you.

Since it is not your mass that matters, you are doing something to slow your fall, ie. you are introducing extra friction into the equation. Since we have ruled out wax, this remaining cause of friction is most likely either from air resistance or edging. Air resistance is the major reason why downhillers wear spandex and tuck a lot. Since you are smaller than he is, it is most likely not air resistance that is causing you to go slower (unless you are wearing extremely baggy clothing).

So the answer has to be that you are edging more than your husband is and you need to work on reducing this source of friction to increase your speed. Another one of the important things that downhill skiers do to go fast is to try to keep as large a flat surface as they can on the snow. This is because skis generate a very thin film of water to reduce the friction, which is actually what you ride on top of the ice crystals (snow or hard back). To keep a long stiff ski flat on snow at speed to increase the running surface requires a lot of leg muscle, which is another reason why downhillers have really thick thighs. If you see a racer (or anyone for that matter) throwing off a large plume of snow on a turn they are generating lots of friction and loosing speed from the turn.

So I will have to agree with ssh. What you need to do is ski extremely clean lines, being careful not to check your speed or use your edges too much in your turns. If your skis are shorter or not as stiff, you may be inadvertantly checking your speed because you do not feel stable. For example, even though my slalom skis are plenty stable, at 165 vs. 193 for my GS skis I do not go as fast on slaloms (both are race stock Atomics) just because I don't feel as comfortable over 35 mph on the slaloms.

My suggestion would be to rent or borrow a pair of GS skis (like your husband's race tigers) and try a few speed runs with minimal breaking to get a feel for what it takes to go faster some day when you are not skiing with him. This echos the comments from Ghost above.

Finally, your better times in the NASCAR course would tend to confirm that you are a better carver than he is in gates and that you don't have a problem carrying speed while turning. So you probably just need to get used to going faster and using less edges outside the gates to smoke him.

Physicsman could probably give you a more involved explanation, but I suspect that the answer would be similar.
post #33 of 58
The NASCAR course has more to do with her driving skills, Kaj.



post #34 of 58
Quote:
Originally Posted by ssh View Post
The NASCAR course has more to do with her driving skills, Kaj.



Whoops, guess my Freudian slip was showing. Well, NASCAR, NASTAR, let's just hope we get things going faster here...
post #35 of 58
Thread Starter 
I actually got some Race tiger RC's to play with and love them, almost as much as my Nitrous'

I've only raced NASTAR once,(this year), and my husband raced once last year. His time was actually a bit better than mine, except one run when he lost his ski.
My results
His Results

Oddly enough, Speed doesn't intimidate me nearly as much as air. That is one reason I usually don't have trouble staying with the guys, I just want that tiny edge to get past them.
Two things I really wanted to accomplish this year:
Get better in moguls - working on it and loving it!
Get comfy in the air enough to do a helicopter -working on that with somewhat marginal results.
I am okay with a credit card jump and have gotten far more comfortable skiing backwards than I was at the beginning of the season.

I'll just keep working on all my skills and maybe I can be the complete package some day!
post #36 of 58
Thread Starter 
Quote:
Originally Posted by ssh View Post
The NASCAR course has more to do with her driving skills, Kaj.



Now if you want to talk Nascar, I have two sets of Busch and Cup tickets for Richmond Virgina in May. Lets go!
post #37 of 58
Hi Trekchick,
A dumb idea maybe but might make for an interesting experiment. Go to a Scuba shop and get a weight belt and weights. Add 30-40 lbs and see what happens.

My serious input is that cleaner transitions are where you will find the advantage you seek. He who scrubs off the least speed wins. Stated another way, a carving ski is faster then a skidding ski.
If you and hubby both decelerate and accelerate a little in each turn, his extra weight gives him an advantage during the acceleration. If you can ski a cleaner line you should overcome his weight advantage.

Two experiences I've had: 4 years ago, another instructor and I were playing on Heather at the Highlands. I was doing big arcs using the full width of the run, probably getting to within 5-6 feet of the edge. Ed skied straight down the middle, no turns. At the bottom he told me, with a little frustration, he couldn't keep up.

Second: about 17 years ago I watched a metro detroit ski council race at Boyne Mountain. The top 2 women were polar opposites in build. One had thighs that were twice as big as mine. The other had thighs that were about as big as my fore arm. I was told that these 2 dominated those races and no one else came close. The day I watched, the skinny one won. She was rumored to have been a collegiate champion. Watching them taught me that speed in a ski race had to be more about technique then strength and mass.
post #38 of 58
Quote:
Originally Posted by KAZOOSKI View Post
Hi Trekchick,
his extra weight gives him an advantage during the acceleration.
No sir. You're wrong here, that, or I misinterpreted your writing.

A heavy body is accelerated by gravity at the same rate as a light body. The force of gravity on a heavy body is bigger than on a lighter one, but it takes more force to move, that cancels out exactly!
Only when you take in account (air/snow) resistance there might be a difference.
post #39 of 58
Friction on the snow will make a difference....

http://snobear.colorado.edu/Markw/Sn....html#friction

Although it is low, it will still have an effect... Although not on a flat surface, and a lot more math would be involved.. the idea is that Normal Forces (Fn) effect the force of friction (Ffr). More normal forces (Fn) results from more force due to the gravity (Fg). the Force due to Gravity is equal to mass x gravity (weight). so... Weight will effect speed on snow.. the question is.. how much... I don't know the co-effeicient of friction for skis on snow, ski bases on snow, ski edges on snow, waxed, unwaxed... It'd also depend on how hard the snow is, how waxed the skis are, etc... But, theForce of Friction is equal to (Co-efficient of friction * Normal Force) and co-efficients of friction are from 0 - 1.00...

Also, as far as air resistance is concerned, muscle is more dense than fat, so there is more weight packed into a smaller package on a lean person rather than someone with some meat on their bones...
post #40 of 58

I am not a racer

and I never played one. But I like to watch the William's College womens race team train. They train pretty often.

I think if you are trying to get better in moguls and get more comfortable with air and you want to ski faster, then you have too many goals for this season.

This year at the big K, take your lumps. I've skied with you before and I don't think you'll take many.

Feel free to smack Phil in the knee because you can.

I think the equipment, technique suggestions are your best bet.

So, in the off-season, get your stuff. Next season, join a night race league (the local beer league) and practice, practice, practice. The more rewarding goals are those that are earned.

... and get the skin tight body suit. :
post #41 of 58
Thread Starter 
Rob, you rock! I had stowe much fun skiing with you!

Okay:
Narrow my season goals - which isn't too difficult to do. I am more comfortable with air though not big air. Moguls have been nonexistent here until the past few weeks when we finally got some real snow, so my mogul skills have plateau'd. Since I'm going to bumpfest (sorry, phil, bumpphest) I will likely get my dose of moguls. I have had some extremely generous offers to give me mogul tips while at Kton.

Quote:
Feel free to smack Phil in the knee because you can.
I like the way you think


As for speed, I'm really quite happy with my current speed, but I really want to know how much the size impacts the speed. This thread has answered a lot of my questions on this matter.

After Stowe, I really cleaned up my skiing, thanks to Jeb!!!!! At first I felt like I slowed way down, which was fine, because I was paying attention to skills, drills, and form. It didn't take long to kick it up a notch with the new tools.

The Boyz don't have to wait for me at the chair, which is a good thing because my ears may bleed from their complaints if I made them wait:
Quote:
... and get the skin tight body suit. :
Speed suit!? You nuts?????
post #42 of 58
Settle the matter

Once and for all!

Put 65# of rocks in a back pack and ski with that "Speed secret" on your back all day. Pick an icey day if you want to see a real turn of speed. Sometime, soon after noon if I guess correctly, you will find your legs SO TIRED that turns will be the farthest thing from your thoughts.

Point 'em down hill and watch those boyz drool as you are CONSISTANTLY the first one to the bottom!

Can we say WEEE HAA!

All in good fun

CalG
post #43 of 58

Weight & Mass have no effect on how fast you ski!

As per my previous post, weight and mass have no effect on terminal velocity in a fall. In other words, all other things being equal, a 200 lb skier and a 120 lb skier will arrive at the bottom of the hill at the same time. This has been an established scientific principle since Galileo performed the experiment in the 16th century. The anecdote is that he dropped two balls of unequal weight/mass from the campanille in Pisa (aka the leaning tower) and both arrived at the bottom at the same time. So anyone who posted anything about gaining weight, rocks, weight belts, etc. must have flunked high school physics:

Simple gravity equation

When you drop an object from a height that is relatively close to the Earth, the gravitational force pulling it to the ground is:
F = m*g
where
  • F is the force of gravity on an object
  • m is the mass of the falling object
  • g is the acceleration due to gravity on Earth
The value of g is 32 ft/s2 (feet per second squared) or 9.8 m/s2 (meters per second squared). The units are sometimes written ft/s/s or m/s/s.
Note: The value of g varies at different parts of the Earth. It is less at the equator due to the centrifugal force from the spin of the Earth. The value at the poles is g = 9.8640 m/s2 and at the equator g = 9.7982 m/s2. You can use g = 9.8 m/s2 for most calculations. Since g is a constant, it means that all objects fall to the earth at the same rate of acceleration, no matter how much they weigh.
Relatively close to Earth means not so far up that you are entering outer space.

Gravity equations

From the equation F = m*g, you can determine the relationships between velocity, distance and time for a falling object.

Independent of mass

Force is defined as mass times acceleration F = m*a. Thus m*a = m*g and a = g. That means that the acceleration due to gravity is independent of the mass. It also applies to the velocity, distance and time it takes an object to fall. They are all independent of the mass of the object.
It looks so simple, but many people don't understand that all objects fall at the same rate, independent of their mass, assuming air resistance is negligible.

Velocity equation

Since acceleration is the change in velocity over time and since g is a constant, the velocity v of a falling object is:
v = g*t
where t is the time in seconds after it is dropped.
In other words, if an object drops for 2 seconds, its velocity will be v = 32 ft/s2 * 2 s = 64 ft/sec.
Also, since t = v/g, if an object is falling at a rate of 29.4 meters/sec, it has been falling for t = 29.4 m/s divided by 9.8 m/s/s = 3 seconds.


In short, TC needs to reduce whatever forces are slowing her rate of fall and the source of these forces are most likely her edges. (Other contributing factors could be air resistance such as needing a speed suit, and other sources of friction such as improper waxing).
post #44 of 58
Thread Starter 
Thanks for the physics lesson
I was never a really good student, gut that is the information for which I was seeking.
post #45 of 58
Quote:
Originally Posted by trekchick View Post
Thanks for the physics lesson
I was never a really good student...
Yeah, same here. My prof got all out of joint over my answer to the question of the velocity those falling objects were travelling when they hit the ground - zero.
post #46 of 58
Drag force of cohesion of snow on skis is a constant that does not increase along with the acceleration force mg sin theta, and friction force umg cos theta. With more mass the cohesion is a lower percentage of the total force.

Therefore, fill your pockets with sand!
post #47 of 58
Thread Starter 
Quote:
Originally Posted by Ghost View Post
Drag force of cohesion of snow on skis is a constant that does not increase along with the acceleration force mg sin theta, and friction force umg cos theta. With more mass the cohesion is a lower percentage of the total force.

Therefore, fill your pockets with sand!
If I fill my pockets with snickers snackers, In theory, As I eat them I'll maintain the same weight and get the satisfaction...............Because Snickers satisfies


In all seriousness, I really did start this thread because I wanted to clear some stuff up in my head about the physical nature of mass, skiing, and technique.
I'm getting a lot out of the responses, both serious and playful.

Cgeib, maybe we are more alike that I'dlike to admit.
post #48 of 58
Thread Starter 
Quote:
Originally Posted by ski now work later View Post
Skiing is such a metaphor for life. Conditions change, equipment needs adjusting, and checking one's ego at the door is always useful.
This quote from SNWL made an impact on me so I thought I'd share.
Some significant "Checking of the ego at the door" has happened in my skiing this year. And I've made strides to really be open to tips and advice from people I hold in high regard. These instructors have Inspired a new skier in me!!
Here's a story about my weekend of skiing.
For purposes of this story you should know DH=Dear Husband.


I had not been on my Blizzard Mag Sl's much and really hadn't had the chance to ski them, like they were meant to be skied.
Saturday We (DH, +3 friends) hit the hill for first chair. Firm groomers called for the SL's!
I did a few runs doing some drills that Kneale Brownson taught me, as well as one that Robin Barnes taught me, so I took it easy and "did the drills". DH picked on me a bit about keeping up and how they had to wait for me at the lift to which I said...."no you don't. Go ahead!"

By the 4th run of the day, I decided to open it up!
Within 2 runs, I caught up with Da Boyz!
My husband with his old school stance, on his Volkl RaceTiger GS 180 cm, and lil o' me on my Teensy weensy (men never like to hear the term teensy weensy) Blizzard Sl's 155 cm. I smoked him!!!
Every lap, lap after lap. He had to straight line to keep up with me and only passed me when he was totally out of control!
The more you turn (clean turns)on those SL's the faster you go!!!
His buddies proceeded to be entertained by the FACT that DH was chasing his tail to chase my tail!
Gawd that was FUN!!!
Gives a whole new meaning to the term : Smoke 'em if you got 'em!!
post #49 of 58
Check out the big brain on Viking!

Helicopters and skiing backwards????

What are you 15?

Nice work on beating DH! That'll show him!
post #50 of 58
Told you.
post #51 of 58
I don't feel like reading the whole thread again, so if this has already been mentioned excuse my laziness. I would think that a more massive skier will be slower than a lighter skier, since he will offer up more surface area to interact with the wind resistance, and a tad bit more snow friction. However, as is the case with WC skiers, where even if all things are equal (technique, mountain, gear) save for the size of the skier, the male skier, being more muscular will be able to handle the forces better than the equally talented yet smaller profile female, I assume cancelling out her advantage with regards to wind resistance, thereby making him more successful at achieving speed.

Now Trek, were you wearing some hot pants? Was DH wearing extra baggy clothes? Not downgrading your win, a win is a win, congrats, but maybe you just happened on the right formula that day.

A buddy of mine, who admittedly does not ski as well as I, was beating me all day long a few seasons ago. With all my waxing, and ski-fanaticism, here is this guy who maybe skis 4 times a year, putting some hurt on me. BUT! He had vintage style tight ski pants, and a relatively close fitting jacket, I was wearing contemporary baggy stuff. I finally put 2 and 2 together, froze for a little while and lost the jacket; he never got even close to beating me again.
post #52 of 58
When I was learning to telemark and snowboard, I was having trouble keeping up with a friend of mine. In the afternoon, I switched back to my alpine skis and I figured "OK, now I'll show him who's boss." I took off and was flying down the hill, I thought I was skiing much faster than my friend could ski. Then I saw him in my peripheral vision catching up! I felt I was already going a little faster than I should have been, and I knew my less skilled friend was going too fast for his ability level, so I gave up, I slowed down and let him go past me. Moments later he was down with a broken femur. I still feel guilty about that.

I really don't get racing on an open slope. Who cares? I assume you were skiing a small hill, even if your husband was going twice as fast, he probably would have to wait less than one minute. You Midwesterners need to relax, leave that rush rush rush rat race pace at the workplace, ski free and easy.
post #53 of 58
Quote:
Originally Posted by Trekchick View Post
Oddly enough, Speed doesn't intimidate me nearly as much as air.
Then you say you smoke 'em on 155 Blizzard SLs.


The next bit is pure conjecture, but it was fun to write:


OK, listen up.

It's simple - it's vertical movement.

After Balance, the first thing that most people can improve is vertical movement -- ie. flexion and extension.

Fear of air? Go rigid and fly maybe?

How about pre-jumping or absorbing instead? Absorbing uses LOTS of vertical movements. If you FEAR air, it may be that you won't put yourself in the position that you'll need that much vertical movement to accomodate the bumps/rolls of the hill.

Which leads to why the Blizzards work for you -- they overpower you.

The turn ends not so much because you choose to let it go, but becuase they've edged so quickly and strongly that you must let it go. So instead of you flexing to release, the ski moves across strongly and makes you release.

You are letting it go sooner than you would the other skis. This means you are spending less time skiing across the hill => more time in the fall line => more speed.

You say there are no fears of speed, because sense of balance is ok. OTOH, Fear of air (which is caused by bumps) is a problem, because of a lack of ability to absorb/flex. The upshot is you hold onto the turn too long...... you "complete the turn", to control speed to avoid the air that you'll get off any rolls.

I would work on squatting between turns and getting long at apex. You'll kick on any ski then.

Here is an example drill.

Squats between turns, pushing the arms out and ahead at the moment of flexion -- you are lowest to the snow here..... Then as you extend into the new turn, push the body forwards and extend out of the boot cuffs. Open, the arms as if brushing past curtains as you extend. The direction of movement is diagonal, directed to be longest at the apex of the new turn.

Here is a video that shows the extent of this movement in real life action.

http://www.youtube.com/watch?v=KwmjkA4l6Ic

As a drill, you should be able to get your butt lower than your knees, but a 90 degree squat is good enough. You can even flex do it so fast that the skis rise off the snow.

Once you can master this flexion/extension drill, the skis won't matter anymore. You'll kick DH @ss any time.
post #54 of 58
Quote:
Originally Posted by BigE View Post
Then you say you smoke 'em on 155 Blizzard SLs.


The next bit is pure conjecture, but it was fun to write:


OK, listen up.

It's simple - it's vertical movement.

After Balance, the first thing that most people can improve is vertical movement -- ie. flexion and extension.

Fear of air? Go rigid and fly maybe?

How about pre-jumping or absorbing instead? Absorbing uses LOTS of vertical movements. If you FEAR air, it may be that you won't put yourself in the position that you'll need that much vertical movement to accomodate the bumps/rolls of the hill.

Which leads to why the Blizzards work for you -- they overpower you.

The turn ends not so much because you choose to let it go, but becuase they've edged so quickly and strongly that you must let it go. So instead of you flexing to release, the ski moves across strongly and makes you release.

You are letting it go sooner than you would the other skis. This means you are spending less time skiing across the hill => more time in the fall line => more speed.

You say there are no fears of speed, because sense of balance is ok. OTOH, Fear of air (which is caused by bumps) is a problem, because of a lack of ability to absorb/flex. The upshot is you hold onto the turn too long...... you "complete the turn", to control speed to avoid the air that you'll get off any rolls.

I would work on squatting between turns and getting long at apex. You'll kick on any ski then.

Here is an example drill.

Squats between turns, pushing the arms out and ahead at the moment of flexion -- you are lowest to the snow here..... Then as you extend into the new turn, push the body forwards and extend out of the boot cuffs. Open, the arms as if brushing past curtains as you extend. The direction of movement is diagonal, directed to be longest at the apex of the new turn.

Here is a video that shows the extent of this movement in real life action.

http://www.youtube.com/watch?v=KwmjkA4l6Ic

As a drill, you should be able to get your butt lower than your knees, but a 90 degree squat is good enough. You can even flex do it so fast that the skis rise off the snow.

Once you can master this flexion/extension drill, the skis won't matter anymore. You'll kick DH @ss any time.
Ill try your advice as well, I am in the same boat as TC, speed causes little fear, but getting airborne always causes a red alert for me.
post #55 of 58
trek,

Quote:
What Roll does body mass play in my ability to keep up with the boyz?
As one of the boyz, I am 80# lighter than some I ski with and they can pass me on gentle catwalks when we are just gliding. When on the steeps, I can rip past them like they are going backwards and today with very warm temps, I took them in the bumps. The snow on the bumps was so soft (and wet) that the skis would sink in 6" very suddenly. The heavier guys were very envious that I wasn't sinking in in as much as they did, and that I could retract much easier than they could. Bottom line, I was waiting for them at the bottom (again).

Quote:
Me: 5'6" 130#
Perfect, be glad you don't weigh more.

RW
post #56 of 58
I'd think being on edge would help. It becomes more important when skiing the fatt skis these days too because you have to angle them over more. I saw this the other day skiing with qk9 - once carving correctly his speed increased a lot on the same skis and slope.

But I'm with that other guy - too much speed means more force if you have a sudden accidental stop
post #57 of 58
not to beat a dead horse or anything like that...but some of the physics being tossed around in this thread is way oversimplified.

Quote:
Force is defined as mass times acceleration F = m*a. Thus m*a = m*g and a = g. That means that the acceleration due to gravity is independent of the mass. It also applies to the velocity, distance and time it takes an object to fall. They are all independent of the mass of the object.
It looks so simple, but many people don't understand that all objects fall at the same rate, independent of their mass, assuming air resistance is negligible.
The key phrase is "...assuming air resistance is negligible".
It is not, at least not in Earth's atmosphere (where I assume that most of us ski).

Drop a feather and a rock. I'm sure you know that they do not have the same acceleration in our atmosphere. However, if you perform this experiment in a vacuum, they will have the same acceleration.

Why is this?
This is because force of air resistance is directly proportional to the cross-sectional area of the falling object, which in turn is proportional to the SQUARE of its dimension, while the force of gravity is directly proportional to the volume of the falling object, which in turn is proportional to the CUBE of its dimension. Thus, for objects of the same density, air resistance becomes proportionally smaller for larger (and hence more massive) objects.

See http://en.wikipedia.org/wiki/Drag_(physics) for more details.

So the long and short of it is that all other things being equal, Trekchick's terminal velocity on skis will be slower than DH's terminal velocity BECAUSE she is smaller/lighter. And this is not a contradiction of Galileo or any physics at all. This is because it is not OK to ignore the effect of air resistance in this discussion.

Regards,
Andrew
post #58 of 58
Thread Starter 
Quote:
Originally Posted by Ron White View Post
trek,



As one of the boyz, I am 80# lighter than some I ski with and they can pass me on gentle catwalks when we are just gliding. When on the steeps, I can rip past them like they are going backwards and today with very warm temps, I took them in the bumps. The snow on the bumps was so soft (and wet) that the skis would sink in 6" very suddenly. The heavier guys were very envious that I wasn't sinking in in as much as they did, and that I could retract much easier than they could. Bottom line, I was waiting for them at the bottom (again).



Perfect, be glad you don't weigh more.

RW
The drill/tips that Kneale taught me helped clean up my edge to edge without scrubbing off speed with the tail skid. What a huge difference!!!
I only wish I were eloquent enough to describe it myself. I understand it, but can't explain it.
I'm with you on the speed thing now. Catwalks, flat run outs, and they pull away from me, but get me on the slope and I can smoke him.

Telerod, its not my goal to race my husband and "da boyz" but its good to know I can if I want to!

Ron, as for the weight, I dropped 10 lbs since I originally posted this and I wish I had that 10 lbs back.
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