ObSki: another run with flatboarding

On Jun 6, 12:27 pm, klaus wrote:
taichiskiing wrote:

Yup, it is formally known in physics as "angular acceleration."

No it's not.

Yes. It is.

He is talking about centripetal acceleration which exists
even when there is no angular acceleration or slipping
of the skis, nonpartitioned one.

Not really, the centripetal force does not exist in a straight line
motion (by Newton' first Laws of Motion). And the centripetal force
does not come alone, (given Newton's third Laws of Motion which stated
that for a given force/action there's an equal magnitude but opposite
in direction force in reaction,) there's also the centrifugal force.
The interaction of these two forces determines the curvature of the
path that the object is traveling: (1) when centripetal force equals
the centrifugal force, the curvature of the path is a circle (a
balanced turn,) (2) centripetal centrifugal, the radius of the turn
shortens, the curvature of the path turns inward (skidding), and (3)
centrifugal centripetal, the radius of the turn lengthens, the
curvature of the path turns outward (slipping). And this argument can
be verified by swinging a rock attached on a string in circle.

Moreover, in skiing, the centripetal force happens at the feet/skis,
and the centrifugal force appears the head, so to maintain the balance
during a turn, some kind of angulation is required in high level
skiing.

HIH,
IS


-klaus

taichiskiing wrote:

Not really, the centripetal force does not exist in a straight line
motion (by Newton' first Laws of Motion). And the centripetal force
does not come alone, (given Newton's third Laws of Motion which stated
that for a given force/action there's an equal magnitude but opposite
in direction force in reaction,) there's also the centrifugal force.
The interaction of these two forces determines the curvature of the
path that the object is traveling: (1) when centripetal force equals
the centrifugal force, the curvature of the path is a circle (a
balanced turn,) (2) centripetal centrifugal, the radius of the turn
shortens, the curvature of the path turns inward (skidding), and (3)
centrifugal centripetal, the radius of the turn lengthens, the
curvature of the path turns outward (slipping). And this argument can
be verified by swinging a rock attached on a string in circle.

Wrong. The centripetal force is always equal to the apparent centrifugal force:
http://www.answers.com/topic/centrifugal-force

Or so says Newton's First Law. The angulation of the body is required
to get a component of gravity to counter the torque which appears due
to the fact that the center of mass is not atthe point of contact ofthe
skis.

Furthermore, skidding and slipping have nothing to due with constant
radius turning. If a train is on a track of increasing radius, is it
slipping? Or skidding?

A perfect ski carve has no slipping or sliding:

http://www.citebase.org/abstract?id=...hysics/0310086


Moreover, in skiing, the centripetal force happens at the feet/skis,
and the centrifugal force appears the head, so to maintain the balance
during a turn, some kind of angulation is required in high level
skiing.

Wrong again. Both forces appear along the entire body. And in my 25
years of biomechanics work, they are usually assumed to act at the
center of mass for simplicity in modelling of rigid bodies.

A physisist you are not.

-klaus

klaus wrote:

Furthermore, skidding and slipping have nothing to due with constant
radius turning. If a train is on a track of increasing radius, is it
slipping? Or skidding?

Ah, summer. The time to kick back and reminisce about cabbages, kings,
and Train Served Backcountry:

http://www.taomartialarts.com/crn/crn_p_ht_xc.jpg

So how's the moose? Are the cheerleaders back yet this year?

//Walt

On Jun 7, 9:56 am, taichiskiing
wrote:
On Jun 6, 12:27 pm, klaus wrote:

taichiskiing wrote:

Yup, it is formally known in physics as "angular acceleration."

No it's not.

Yes. It is.

He is talking about centripetal acceleration which exists
even when there is no angular acceleration or slipping
of the skis, nonpartitioned one.

Not really, the centripetal force does not exist in a straight line
motion (by Newton' first Laws of Motion). And the centripetal force
does not come alone, (given Newton's third Laws of Motion which stated
that for a given force/action there's an equal magnitude but opposite
in direction force in reaction,) there's also the centrifugal force.
The interaction of these two forces determines the curvature of the
path that the object is traveling: (1) when centripetal force equals
the centrifugal force, the curvature of the path is a circle (a
balanced turn,) (2) centripetal centrifugal, the radius of the turn
shortens, the curvature of the path turns inward (skidding), and (3)
centrifugal centripetal, the radius of the turn lengthens, the
curvature of the path turns outward (slipping). And this argument can
be verified by swinging a rock attached on a string in circle.

Moreover, in skiing, the centripetal force happens at the feet/skis,
and the centrifugal force appears the head, so to maintain the balance
during a turn, some kind of angulation is required in high level
skiing.

Yep. Definitely "Jeff Davis" physics.

In article . com,
taichiskiing wrote:

Not really, the centripetal force does not exist in a straight line
motion (by Newton' first Laws of Motion).

To understand Newton's first law of motion you must understand that an
object in motion is an object not in motion. Thus moving is not moving,
and at rest is not actually at resting.

And the centripetal force
does not come alone, (given Newton's third Laws of Motion which stated
that for a given force/action there's an equal magnitude but opposite
in direction force in reaction,) there's also the centrifugal force.

No discussion of physics on the internets would ever be complete without
at least mentioning the centrifugal force.

Moreover, in skiing, the centripetal force happens at the feet/skis,
and the centrifugal force appears the head, so to maintain the balance
during a turn, some kind of angulation is required in high level
skiing.

This is clearly lifted out of some fancy college "high level" physics
text! Ordinary people don't walk around with this kind of advanced
knowledge.

So what force is described by the frantic arm flapping? Is that the
angulation?

Dave

"Dave Cartman" wrote in message ...
In article . com,
taichiskiing wrote:

Not really, the centripetal force does not exist in a straight line
motion (by Newton' first Laws of Motion).

To understand Newton's first law of motion you must understand that an
object in motion is an object not in motion. Thus moving is not moving,
and at rest is not actually at resting.

And the centripetal force
does not come alone, (given Newton's third Laws of Motion which stated
that for a given force/action there's an equal magnitude but opposite
in direction force in reaction,) there's also the centrifugal force.

No discussion of physics on the internets would ever be complete without
at least mentioning the centrifugal force.

Moreover, in skiing, the centripetal force happens at the feet/skis,
and the centrifugal force appears the head, so to maintain the balance
during a turn, some kind of angulation is required in high level
skiing.

This is clearly lifted out of some fancy college "high level" physics
text! Ordinary people don't walk around with this kind of advanced
knowledge.

So what force is described by the frantic arm flapping? Is that the
angulation?

Dave

Diligent practice of Tai Chi raises one to a higher plane of Zen existence,
where the laws of motion are different, and stationary arms only
*appear* to be moving like an orchestra conductor's.
We unenlightened tyros are not expected to comprehend, Dave.

Bob F wrote:
"taichiskiing" wrote in message
On Jun 5, 11:26 am, "Bob F" wrote:

...I'm always wanting to learn new things...

"Can't learn with a full-cup."

What exactly are you saying?

That is a special mystical eastern way of saying
"You All Suck".

ant
--
Don't try to reply to my email addy:
I'm borrowing that of the latest
scammer/spammer

"Bob F" wrote in message


...I'm always wanting to learn new things...

"Can't learn with a full-cup."

What exactly are you saying?


As far as I can tell, he means that because he knows less than you do, he
can figure things out better. There is in fact some precedent for operating
this way. The Bush administration springs to mind.

I think taichi meant to say this (adapted from James Harris, well-
known mathematical genius):

The Fate of the Species
If you think for one moment that truth
cares about the misery you might feel now after viewing my video
and realizing there is no way to object
then you are so far from being a real skier
that you are getting a major favor by learning how
wrong you have been before.

Taichi skiing is about the search for truth,
so sometimes people wander down the wrong path, and can
do so for a while, but if you believe that truth is
actually important, then you can be thankful when you
are turned back.

But that is not necessarily easy.

And if you want easy, go find something else to do.

The technique tells the tale. My video closes the door
on stylisitc objections.

If you wish to turn to human interest ones that is a
choice you can make. Worry about how you feel or how
everyone should feel and curse new technique discovery.

And then think about where our species would be if
people like you ever won.

You tried to win here and hold back skiing theory. If
people like you had won thousands of years ago we would
not have flatboarding today.

And without flatboarding we would not have human civilization.

You have to lose no matter what you feel so that there
IS a future.

These kind of battles are always about the fate of the
species.

It's for all the marbles. When ignorance wins, we all
lose.

Norm wrote:
"Bob F" wrote in message


...I'm always wanting to learn new things...

"Can't learn with a full-cup."

What exactly are you saying?



As far as I can tell, he means that because he knows less than you do, he
can figure things out better. There is in fact some precedent for operating
this way. The Bush administration springs to mind.

No, no, no. He means that women with big tits are thick.