Can Snowboarders and skiiers be friends?

Neil Gendzwill wrote:
Walt wrote:
fotoobscura wrote:

Skii's take up less surface area. Less surface area == less friction
== more speed. There really is no arguing that.

Um....yes there is. Get out your Physics 101 text. Friction force is
equal to (weight) x (coefficient of friction). It's independent of
surface area. And since ski and snowboard bases are made out of the
same materials (ptex) the coefficient of friction is the same.

Yeah, well physics 101 is... inadequate usually, to explain the real
world. If the coefficient of friction is all there is to it, then
explain why drag racers use big, wide tires. Seems they could save a
lot of money using small skinny ones if that simple formula held true
all the time.

How snowboards and skis interact with the snow surface is probably more
fluid dynamics than anything else. It's complex, and I don't claim to
know much about it other than it can't be reduced to a coefficient of
friction and the weight bearing down on it.

I wasn't claiming that coefficient of friction explains everything, just
refuting the assertion that less surface area == less friction.

I agree that it's complex and way beyond the scope of Physics 101.

--
//-Walt
//
// There is no Völkl Conspiracy

Neil Gendzwill wrote:
Yeah, well physics 101 is... inadequate usually, to explain the real
world. If the coefficient of friction is all there is to it, then
explain why drag racers use big, wide tires.


A wide tire results in less psi (pounds per square inch) because there
is more tire in contact with the road. However, wide tires dissipate
heat better than narrow tires because there is more surface area.
Therefore a wide tire can use a different compound (stickier) than a
narrow tire if the situation calls for that. A narrow tire at high speed
would melt, which is usually not a good thing to have happen.

Dean

Walt wrote:
Neil Gendzwill wrote:

Walt wrote:

fotoobscura wrote:

Skii's take up less surface area. Less surface area == less friction
== more speed. There really is no arguing that.


Um....yes there is. Get out your Physics 101 text. Friction force
is equal to (weight) x (coefficient of friction). It's independent
of surface area. And since ski and snowboard bases are made out of
the same materials (ptex) the coefficient of friction is the same.


Yeah, well physics 101 is... inadequate usually, to explain the real
world. If the coefficient of friction is all there is to it, then
explain why drag racers use big, wide tires. Seems they could save a
lot of money using small skinny ones if that simple formula held true
all the time.

How snowboards and skis interact with the snow surface is probably
more fluid dynamics than anything else. It's complex, and I don't
claim to know much about it other than it can't be reduced to a
coefficient of friction and the weight bearing down on it.


I wasn't claiming that coefficient of friction explains everything, just
refuting the assertion that less surface area == less friction.

I agree that it's complex and way beyond the scope of Physics 101.



Less surface area = less friction: YES

Less surface area = more pressu YES

the tendency of snowboards and skis is that they ride above the snow...
However the snow surface isn't a solid surface, it more or less acts
like fluid. Therefore less surface area = less floatation.

Since you need speed to keep your plank "afloat" so that it isn't
digging into the snow, it means that it takes a skier higher speed to
float the same as a snowboarder. Therefore it really has nothing to do
with speed but with acceleration. Like a normal boat versus a hydrofoil,
a hydrofoil can reach top speed much quicker than a boat because it
reaches a speed where it's contact with the surface is no longer that of
direct resistance but just friction.

So basically a snowboard will get to a certain speed faster than skis
because it can reach "planing speed" faster.

(Planing is a lot faster than pushing against water or any other fluids)

Dean wrote:

Neil Gendzwill wrote:

Yeah, well physics 101 is... inadequate usually, to explain the real
world. If the coefficient of friction is all there is to it, then
explain why drag racers use big, wide tires.



A wide tire results in less psi (pounds per square inch) because there
is more tire in contact with the road. However, wide tires dissipate
heat better than narrow tires because there is more surface area.
Therefore a wide tire can use a different compound (stickier) than a
narrow tire if the situation calls for that. A narrow tire at high speed
would melt, which is usually not a good thing to have happen.

Dean

Drag racers need big fat tires because they need as much friction as
possible. the contact point on a wheel, relative to the ground, is
stationary. To achieve maximum acceleration the wheel needs as much
friction as possible. This is also why anti-lock breaks work better than
locking your tires. When a wheel is locked, the wheel slides across the
pavement. Coefficient of stationary friction no longer applies.... now
you have coefficient of kinetic friction, which is much lower than
stationary. However a wheel that's not slipping has the most friction
with the ground.

stu

Waco Paco wrote:

Drag racers need big fat tires because they need as much friction as
possible. the contact point on a wheel, relative to the ground, is
stationary. To achieve maximum acceleration the wheel needs as much
friction as possible.

Yeah, but the problem is if you buy the coefficient of friction
argument, it doesn't matter how big the tire is - it has the same amount
of friction, determined by the coefficient and the weight of the car.

But as you've pointed out, there's kinetic friction and as Dean points
out there's materials breakdown to consider and and and ... my point
being, it's complicated. The real world is tricky to explain to a
classroom of freshmen. That's why they always frame the problems with a
bunch of assumptions.

Speaking of air resistance, that's another big reason skiers go faster -
they can get into a better tuck.

Neil

Neil Gendzwill wrote:
Speaking of air resistance, that's another big reason skiers go faster they can get into a better tuck.


On the snowdvd.com video there is a ski racer shown in airfoiled
clothing. Something is holding the airfoil shape in the pants and arms.

Dean

fotoobscura wrote:

I am a snowboarder and I have yet to see a snowboard exceed the speed
of skiis. Its quite simple, actually (and true!)

Skii's take up less surface area. Less surface area == less friction
== more speed.

Yeah, thats why the top downhill skiers use really small skis, say
40cms, so they have less surface area letting them go that much faster.

I really dont think its quite that simple. Time down the mountain is a
function of many more things than friction. Control being one of the
more important ones. Of course if all you were talking about was
straightline speed, the rider having the ability to control whatever
speed he could achieve on whatever he chose to strap to his feet, you
may be right. It is, however, hypothetical.

Si

On Tue, 15 Mar 2005 17:22:08 GMT, Robert Stevahn
allegedly wrote:

It's no problem boarding with skiiers, although expert
skiiers will get down the mountain faster than expert boarders.

Whilst this is generally true, there are exceptions.

On the flat sections, I always seem to pass the skiers if they are not
polling or skating along. In a simple run out with no external help, I
always get by.

Also, in powder, the additional float of the board will allow for easy
cruising past the skiers.

Inbounds on pisted runs, skiers seem to have the advantage.

- Dave.

--
The only powder to get high on, falls from the sky.
http://www.vpas.org/ - Snowboarding the worlds pow pow -
Securing your e-mail

The Snowboard FAQ lives here - http://rssFAQ.org/

On Wed, 16 Mar 2005 07:24:03 GMT, "Bryan"
wrote:


"Dean" wrote in message ...
Bryan wrote:
And why do boarders sit down in the middle of runs?

There are two questions: Why do they sit? Why do they sit in the middle
of runs?

After great consideration I've concluded that the answer is: Because
they can and standing still on a board is very difficult. Sitting with
skis probably isn't realistic which is why some skiers stand in the
middle of runs.

If you want to know why they sit in the middle of runs to socialize
rather than sitting on a side, that's probably because they are young
and aren't thinking. I don't see older boarders sitting in the middle of
runs. We go to the edge to sit and sooth our aching legs and wobbly
knees or to admire the view. I've had to tell kids at the top of hills,


I board, I ski. I learnt skiing first, I learnt boarding afterwards. I
always do a bit of both when I go away. I kinda feel I can be
subjective on this.

IME snowboards don't sit in the middle any more than skiers stand in
the middle. However, the skiers 'tut' because they somehow see
something more lazy about them sitting rather than standing. Boarders
*have* to sit down to stay still when on anything like an incline
because they don't have poles and cannot balance on one edge. IME most
skiers who have never boarded do not appreciate this and get all het
up about nothing. It'd be like asking a skier to hold their position
on a slope whilst facing down in a snow plough position and with no
poles - let's see how long you can hold that before the lactic builds
in your thighs!

Experienced boarders try to come to a stop so as to build up a little
snow under their board as a kind of perch to rest on - but it rarely
works and depends largely on the conditions as to whether it's
possible.


andyt

"Andy Turner" wrote in message
...
On Wed, 16 Mar 2005 07:24:03 GMT, "Bryan"
wrote:


"Dean" wrote in message
...
Bryan wrote:
And why do boarders sit down in the middle of runs?

There are two questions: Why do they sit? Why do they sit in the middle
of runs?

After great consideration I've concluded that the answer is: Because
they can and standing still on a board is very difficult. Sitting with
skis probably isn't realistic which is why some skiers stand in the
middle of runs.

If you want to know why they sit in the middle of runs to socialize
rather than sitting on a side, that's probably because they are young
and aren't thinking. I don't see older boarders sitting in the middle of
runs. We go to the edge to sit and sooth our aching legs and wobbly
knees or to admire the view. I've had to tell kids at the top of hills,


I board, I ski. I learnt skiing first, I learnt boarding afterwards. I
always do a bit of both when I go away. I kinda feel I can be
subjective on this.

IME snowboards don't sit in the middle any more than skiers stand in
the middle. However, the skiers 'tut' because they somehow see
something more lazy about them sitting rather than standing. Boarders
*have* to sit down to stay still when on anything like an incline
because they don't have poles and cannot balance on one edge. IME most
skiers who have never boarded do not appreciate this and get all het
up about nothing. It'd be like asking a skier to hold their position
on a slope whilst facing down in a snow plough position and with no
poles - let's see how long you can hold that before the lactic builds
in your thighs!

Experienced boarders try to come to a stop so as to build up a little
snow under their board as a kind of perch to rest on - but it rarely
works and depends largely on the conditions as to whether it's
possible.


andyt


Informative perspective!