Speed poll

Is the skier in this clip doing 50mph = 80kph as claimed?:

http://www.taomartialarts.com/ski/sk...ghtliningh.wmv

In article om,
Evojeesus wrote:

Is the skier in this clip doing 50mph = 80kph as claimed?:

http://www.taomartialarts.com/ski/sk...ghtliningh.wmv

There are lots of ways to approach this:

Terminal velocity for a person in freefall is about 120 mph. On a 30
degree slope such as that one, the force down the slope is half and
since air resistance is proportional to velocity, 60 mph is as fast as
someone could go if there were no other frictional forces. But there
a the skis on the snow.

The coefficient of kinetic friction for skis on wet snow is about 0.1.
So the friction of the skis on the snow on a slope of 30 degrees is
equal to 3^(1/2)/2 * 0.1, or about 8.5% of the skiers weight.

That reduces the force of one half the skier's weight already mentioned
by 17%; reducing the absolute maximum speed on a 30 degree slope to 49.8
mph.



One can also look at the video.

50 mph is 22.35 m/s. On 175 cm skis, that's equal to just about 12.75
lengths a second. Or when you divide by the frame rate of the video
(29.98), 0.42 ski lengths per frame.

Now for most of the video it's almost impossible to judge how far the
image moves in any frame, but at the end it's clear that the speed is
less than .25 ski lengths per frame.

Or less than 29.3 mph.
--
"I always read what is posted, as I don't share your habits." -- "Upon
rereading your original post, I see that I have been mistaken in what I wrote.
I apologize for my mistaken accuastions and insults." -- Edwin

On May 23, 9:47 pm, Richard Henry wrote:
On May 23, 9:56 am, Evojeesus wrote:

Is the skier in this clip doing 50mph = 80kph as claimed?:

http://www.taomartialarts.com/ski/sk...ghtliningh.wmv

In my expert opinion, it would be impossible to do 50 MPH on the slope
depicted from a standing start without dropping into a tuck. Standing
upright with arms outreached is about the worst position for drag a
skier can stand in.

Did you factor in the fact that he has no poles?

On 23 May 2007 09:56:59 -0700, Evojeesus
wrote:

Is the skier in this clip doing 50mph = 80kph as claimed?:

http://www.taomartialarts.com/ski/sk...ghtliningh.wmv


5280 feet in a mile, so 50 MPH=264,000 feet per hour.

Or 4400 feet per minute.

Or 73 feet per second.

As the clip nears its end, if you start when he crests the little rise
at about the 12 second mark, and count off two seconds, you can laugh
yourself silly at the suggestion that he covers almost half of a
football field in that period.

bw

On May 23, 11:49 am, Marty wrote:
On May 23, 10:56 am, Evojeesus wrote:

Is the skier in this clip doing 50mph = 80kph as claimed?:
http://www.taomartialarts.com/ski/sk...ghtliningh.wmv

I'm not sure, but, I don't think so. Maybe upper 30's?

World Cup is the iciest trail at the Heavenly, because it is at the
base level, the snow melts during the day and groomed every night. If
you dare to go straightlining, you'd hit 50 mph at just above where I
started to "turn." If the snow is mushy, then you may only hit about
40 mph or less.


I am pretty sure MVG is doing 50+ here in this GS (he looks
fast -even in slow motion):

http://youcanski.com/video/gruenigen_gs2.m1v

I post that video to show folks what skiing at high speed
(with turns) is SUPPOSED to look like.

No, that's racing; I'd like to see how he does in Chinese Downhill
(top to bottom, find your own line, and everything goes). (Line
choosing remains one of toughest skills in serious skiing.)

Did you notice his "flatboard-inside-ski-turn" (the last second turn)?
Flatboarding is the sign of high level skiing.


Tai-Chi may be good for defending yourself against an attack - like
from the guy you plowed into while straightlining (or flatboarding or
whatever) and it may be fun for some folks to do on skis. However, if
one were to employ that technique (as stated in the many posts from
the the Tai Chi guy) in any challenging situation, there is a good
chance for a fall.

VtSkier has skied with me and his "eyewitness" report stated
otherwise. What makes you think that your claim has any validity?


In this video: (http://www.taomartialarts.com/ski/
ski_v_is_highjump180h.wmv), he drops his arms (at one point,
behind his upper body and gets into the back seat), widens
his stance and edges his skis to control his speed before
take off. What is up with that?

Actually, that was my "tuck."

That's not Tai-Chi skiing as it's been described over and over
and over. The technique employed before take off is far more
traditional than the wide open "flatboarding" we see in other
videos.Why not flatboard all the way to take off? Never mind - I know why.

Not sure what kind of "Taichi Skiing" that has "been described over
and over and over" that you understood. Nevertheless, give it a shot,
"why" I did "what"?


IS

--
Marty

taichiskiing wrote:


World Cup is the iciest trail at the Heavenly, because it is at the
base level, the snow melts during the day and groomed every night. If
you dare to go straightlining, you'd hit 50 mph at just above where I
started to "turn." If the snow is mushy, then you may only hit about
40 mph or less.

Hey! I know that slope - it's where they hold kid races for Tahoe league
- my boy raced on that course when he was 5. Beat a future US C-Teamer
that race, too. Nice relaxed course, good for the kids.

OK, back to the regularly scheduled discussion.
Or, for the Brits, "Carry On, Regardless."

On May 28, 9:19 am, lal_truckee wrote:
taichiskiing wrote:

World Cup is the iciest trail at the Heavenly, because it is at the
base level, the snow melts during the day and groomed every night. If
you dare to go straightlining, you'd hit 50 mph at just above where I
started to "turn." If the snow is mushy, then you may only hit about
40 mph or less.

Hey! I know that slope - it's where they hold kid races for Tahoe league
- my boy raced on that course when he was 5. Beat a future US C-Teamer
that race, too. Nice relaxed course, good for the kids.

"Brave the new world"?
http://taomartialarts.com/ski/andreawc2.wmv
Andrea, 4-yr old, second year skier.

'later,
IS

On May 29, 8:26 am, taichiskiing
wrote:
On May 28, 9:19 am, lal_truckee wrote:

taichiskiing wrote:

World Cup is the iciest trail at the Heavenly, because it is at the
base level, the snow melts during the day and groomed every night. If
you dare to go straightlining, you'd hit 50 mph at just above where I
started to "turn." If the snow is mushy, then you may only hit about
40 mph or less.

Hey! I know that slope - it's where they hold kid races for Tahoe league
- my boy raced on that course when he was 5. Beat a future US C-Teamer
that race, too. Nice relaxed course, good for the kids.

"Brave the new world"?http://taomartialarts.com/ski/andreawc2.wmv
Andrea, 4-yr old, second year skier.

'later,
IS

What was the point of the video?

On May 28, 8:07 am, taichiskiing
wrote:

http://youcanski.com/video/gruenigen_gs2.m1v

From the above video, we get the following comment:

Did you notice his "flatboard-inside-ski-turn" (the last second turn)?
Flatboarding is the sign of high level skiing.

Okay, I get it. "Flatboarding" is the art of skiing in the transition
of a turn at all times - only with your legs glued together and no ski
poles.

In this video: (http://www.taomartialarts.com/ski/
ski_v_is_highjump180h.wmv), he drops his arms (at one point,
behind his upper body and gets into the back seat), widens
his stance and edges his skis to control his speed before
take off. What is up with that?

Actually, that was my "tuck."

Okay.
--
Marty

On May 29, 10:11 am, Richard Henry wrote:
On May 29, 8:26 am, taichiskiing
wrote:





On May 28, 9:19 am, lal_truckee wrote:

taichiskiing wrote:

World Cup is the iciest trail at the Heavenly, because it is at the
base level, the snow melts during the day and groomed every night. If
you dare to go straightlining, you'd hit 50 mph at just above where I
started to "turn." If the snow is mushy, then you may only hit about
40 mph or less.

Hey! I know that slope - it's where they hold kid races for Tahoe league
- my boy raced on that course when he was 5. Beat a future US C-Teamer
that race, too. Nice relaxed course, good for the kids.

"Brave the new world"?http://taomartialarts.com/ski/andreawc2.wmv
Andrea, 4-yr old, second year skier.

'later,
IS

What was the point of the video?

I think it was to demonstrate the back-seated, wedged, flatboarding
technique - also known as "the tuck".
--
Marty