can one skis be significantly faster

On Mar 13, 4:53 pm, alf ask@me wrote:
Hi,
had a chance to take my new Fisher RX8 to Snowmass/Loveland Co last week
for 4 days. It is pure pleasure and everything what I read was indeed
true, at least to the my level I can verify it at.

One observation though - I was carving behind my friend and some other
guys following their tracks as precisely as possible. The easiness I
could catch them up and the speed it happened was just astonishing. Also
opposite was true, my friend just could not catch me.

So it posses question: is it due to ski itself, skills or what?

Gravity.

On Mar 14, 6:13 am, lal_truckee wrote:
down_hill wrote:
The object
with the largest mass will tend to go faster

Galileo Galilee objects.

Galileo compared a large iron ball with a small iron ball - different
mass, same density, thus mostly cancelling the effects of air
resistance. If he had compared an iron ball with a feather pillow, he
would have published differently.

Richard Henry wrote:
On Mar 14, 6:13 am, lal_truckee wrote:
down_hill wrote:
The object
with the largest mass will tend to go faster
Galileo Galilee objects.

Galileo compared a large iron ball with a small iron ball - different
mass, same density, thus mostly cancelling the effects of air
resistance. If he had compared an iron ball with a feather pillow, he
would have published differently.

Actually Galileo was one of those rare bird for his time.
He actually thought that science should be based on
observation, unlike so many who thought that the writings
of Aristotle were truth in all matters scientific.

I think that if Galileo had tried his experiment with a
feather and a musket ball, he would have OBSERVED the effect
of air resistance on the feather gently floating down and
would have revised his experiment before he published.

lal_truckee wrote:
down_hill wrote:

The object with the largest mass will tend to go faster

Galileo Galilee objects.

Gravitational force is proportional to mass.
Wind resistance is proportional to surface area.

Heavier people have a larger ratio of mass to surface area, so the net
force (gravity - wind resistance) is larger for a heavy person. So
heavier skiers tend to go faster than lighter skiers. Spherical people
will go faster than non-spherical . Spherical cows are quite tasty, no
matter how fast they go.

"Walt" wrote in message
...
Bob F wrote:

Unless you are carving on glare ice, there is more base on the snow than
edge.

It's not ice until it's clear enough to see a fish through it.


I thought it was ice if you could see dirt through it?

Bob

Bob F wrote:
"Walt" wrote in message
...
Bob F wrote:

Unless you are carving on glare ice, there is more base on the snow than
edge.
It's not ice until it's clear enough to see a fish through it.


I thought it was ice if you could see dirt through it?

Nah, if you see dirt through it, it's THIN ice.

On Wed, 14 Mar 2007 15:15:47 UTC, VtSkier wrote:

Richard Henry wrote:
On Mar 14, 6:13 am, lal_truckee wrote:
down_hill wrote:
The object
with the largest mass will tend to go faster
Galileo Galilee objects.

Galileo compared a large iron ball with a small iron ball - different
mass, same density, thus mostly cancelling the effects of air
resistance. If he had compared an iron ball with a feather pillow, he
would have published differently.

Actually Galileo was one of those rare bird for his time.
He actually thought that science should be based on
observation, unlike so many who thought that the writings
of Aristotle were truth in all matters scientific.

I think that if Galileo had tried his experiment with a
feather and a musket ball, he would have OBSERVED the effect
of air resistance on the feather gently floating down and
would have revised his experiment before he published.

He didn't have to try that experiment. Dangerous thing to say about the
almost-inventor of quantitative expermenting! But he knew perfectly well
about air resistance, of course, and referred to it in his most important
work on physics, the Two New Sciences.

BTW the famous experiment from the Leaning Tower may or may not have
happened; many scholars think it didn't. He did some really refined
experiments with rolling balls down inclined planes (slower -- easier to
time with some precision) as well as thought experiments that showed the
foolishness of the idea that things fall with a speed *proportional* to
their weight.


--
Dan Drake

http://www.dandrake.com/
porlockjr.blogspot.com

Walt wrote:

Heavier people have a larger ratio of mass to surface area, so the net
force (gravity - wind resistance) is larger for a heavy person. So
heavier skiers tend to go faster than lighter skiers.

Oversimplification. That depends on the surface roughness of the heavy
vs. light person. See turbulent flow/Reynolds Number.

It's why they put dimples in golf balls.

Which begs the question.. why do many people wax their cars? Why don't
they ding them with a hammer?

-klaus

In article ,
klaus wrote:

Walt wrote:

Heavier people have a larger ratio of mass to surface area, so the net
force (gravity - wind resistance) is larger for a heavy person. So
heavier skiers tend to go faster than lighter skiers.

Oversimplification. That depends on the surface roughness of the heavy
vs. light person. See turbulent flow/Reynolds Number.

Oversimplification maybe, but all other things being equal (same
clothing, etc.) heavier people (i.e. larger people) do fall faster.

With increasing size, the area of an object increases as the square of
the increase in linear dimension while the mass and thus the force of
gravity acting on the mass increases as the cube of linear dimension
increase.

Compare someone 10% larger than someone else. They'll have 21% more drag
(roughly -- yes, Reynolds number change does dictate that it's not
exactly correct), but the force acting on them will be 34% greater.

So the larger person's terminal velocity should be (remembering that
drag increases as the square of the airspeed) approximately
(1.34/1.21)^(1/2) = 1.05 or 5% faster.


It's why they put dimples in golf balls.

Which begs the question.. why do many people wax their cars? Why don't
they ding them with a hammer?

-klaus

--
"The iPhone doesn't have a speaker phone" -- "I checked very carefully" --
"I checked Apple's web pages" -- Edwin on the iPhone and how he missed
the demo of the iPhone speakerphone.

Walt wrote:

Heavier people have a larger ratio of mass to surface area, so the net
force (gravity - wind resistance) is larger for a heavy person. So
heavier skiers tend to go faster than lighter skiers.

Rahlves is not a big guy (except his thighs - huge!)
Miller is a big guy.
Many (not all) of the Austrian DHers are big guys.

Rahlves was generally faster than Miller in the speed events.
Rahlves was often faster than the Austrians in the speed events.

There are too many variables in skiing for heaviest to imply fastest,
even if your analysis was correct (it's not, since speed event racers
tuck, and the smaller guy can reduce his frontal area more effectively,
as well as hold a better "egg.")


For the OP: Not only can one ski model be faster than another, different
skis of the same model (identical construction and bench preparation!)
can be different in speed. Companies that make DH and SG skis for the WC
speed test them looking for pairs that are fastest to provide their
racers. Anything for an edge. Reminds me of an unfortunate accident a
few years ago (at Aspen, I think? Maybe somewhere else?) when an ski
company tester crashed and killed himself doing just this sort of speed
testing, looking for the fastest pairs from suites of identical pairs.