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-   -   Tenkan and Centrifugal Force (http://www.aikiweb.com/forums/showthread.php?t=7761)

Bill Danosky 03-21-2005 02:00 PM

Re: Equitable?
 
I think Tai Chi and Aikido have an apeal to new agers because there is a mystical element within them. That's to say that there appears to be a power at work that's beyond the exertion of normal human strength.

I'm intrigued by this, too, but I explain that there is at least a solid working theory of physics behind every technique. Tenkan exploits the power of centrifugal force, for instance.

Mike Sigman 03-21-2005 02:55 PM

Re: Equitable?
 
Quote:

Bill Danosky wrote:
I think Tai Chi and Aikido have an apeal to new agers because there is a mystical element within them. That's to say that there appears to be a power at work that's beyond the exertion of normal human strength.

"Appears" being the working term. ;)
Quote:

I'm intrigued by this, too, but I explain that there is at least a solid working theory of physics behind every technique. Tenkan exploits the power of centrifugal force, for instance.
Ack! What "centrifugal force" is that? :) Besides, even if there were a centrifugal force (which there's not), I don't think that's the idea behind tenkan; tenkan still uses the opponent's force.

Regards,

Mike

Lorien Lowe 03-21-2005 04:39 PM

Re: Equitable?
 
Quote:

Mike Sigman wrote:
...even if there were a centrifugal force (which there's not)...

Any time there is circular motion, there is a force that can be labeled centrifugal. It may not be fundamental, like gravity or electrostatic or Van Der Waals', but it has to be there if the circular motion isn't decaying.

-LK

mj 03-21-2005 04:51 PM

Re: Equitable?
 
Quote:

Lorien Lowe wrote:
Any time there is circular motion, there is a force that can be labeled centrifugal. It may not be fundamental, like gravity or electrostatic or Van Der Waals', but it has to be there if the circular motion isn't decaying.

-LK

Correct Lorien. Centrifugal and centripetal, basics of aikido.

The very essences of tenkan, extension, kokyu movement and...well..lots :)

Mike Sigman 03-21-2005 04:56 PM

Re: Equitable?
 
Quote:

Lorien Lowe wrote:
Any time there is circular motion, there is a force that can be labeled centrifugal.

It also can be labeled as HonkiDonk Force or anything else you want. But properly speaking, it is inertial force due to rotational movement. ;)

Mike

Mike Sigman 03-21-2005 04:58 PM

Re: Equitable?
 
Quote:

Brion Toss wrote:
Who said anything about reputation? What relevance to reputation do my words bear?

Priceless. :)

Mike

Lorien Lowe 03-21-2005 05:09 PM

Re: Equitable?
 
Centrifugal force is the inertial force specific to rotation. It's a subset, not an alternative.

-LK

Brion Toss 03-21-2005 05:15 PM

Re: Equitable?
 
Quote:

Mike Sigman wrote:
It also can be labeled as HonkiDonk Force or anything else you want. But properly speaking, it is inertial force due to rotational movement. ;)

Mike

"Centrifugal force n. The component of apparent force on a body in curvilinear motion, as observed from that body, that is directed away from the center of curvature or axis of rotation."
American Heritage Dictionary, third edition
This may not be "properly speaking" but it is not incorrect, and it is a long way from HonkiDonk.
Yours,
Brion Toss

Mike Sigman 03-21-2005 05:38 PM

Re: Equitable?
 
Quote:

Brion Toss wrote:
"Centrifugal force n. The component of apparent force on a body in curvilinear motion, as observed from that body, that is directed away from the center of curvature or axis of rotation."
American Heritage Dictionary, third edition
This may not be "properly speaking" but it is not incorrect, and it is a long way from HonkiDonk.

Hoisted by your own petard, Brion. Do you see the word "apparent"? I.e., centrifugal force is not a real force.

Regards,

Mike Sigman

mj 03-21-2005 06:03 PM

Re: Equitable?
 
:D

Bill Danosky 03-21-2005 06:12 PM

Re: Equitable?
 
Quote:

Mike Sigman wrote:
Ack! What "centrifugal force" is that? :) Besides, even if there were a centrifugal force (which there's not), I don't think that's the idea behind tenkan; tenkan still uses the opponent's force.

Mike

I was thinking along the lines that velocity is increased as you shorten the radius of an arc, etc. I have heard that you are the tenkan expert, so I'd be interested in hearing your opinion.

mj 03-21-2005 06:22 PM

Re: Tenkan and Centrifugal Force
 
I would be extremely interested in hearing the opinion of someone who said that centrifugal/petal 'force' (heh) didn't exist.

Unless it was a troll, of course...they would say just anything to argue.

Rupert Atkinson 03-21-2005 06:40 PM

Re: Tenkan and Centrifugal Force
 
I firmly believe that centripetal and centrifugal forces can and should be developed. I have done it myself for ages and am constantly amazed at how weak at technique some people are, even after years of training.

Centripetal force is that what develops when you enter tenkan and draw uke in - sure you use his initial movement, and then add some, and the more you CAN add the more powerful your technique becomes. Centrifugal force is that which is used to spit uke off. Likewise, the more you CAN add, the more powerful your technique becomes.

You can, and should, develop this power.

L. Camejo 03-21-2005 06:55 PM

Re: Tenkan and Centrifugal Force
 
Quote:

Rupert Atkinson wrote:
You can, and should, develop this power.

Reminds me of the progression from Nanahon no Kuzushi to the Ura Waza of the Nage no Kata in Shodokan. It starts off as kuzushi training and then develops into application of kuzushi to throw using the weak lines and then turning while breaking balance along the weak lines.

This is not only the ability to utilise inertia in a circular fashion, but targeted application of force to manipulate the arcs, circles and spirals while keeping Uke off balance imho.
LC:ai::ki:

Mike Sigman 03-21-2005 07:13 PM

Re: Equitable?
 
Quote:

Bill Danosky wrote:
I was thinking along the lines that velocity is increased as you shorten the radius of an arc, etc. I have heard that you are the tenkan expert, so I'd be interested in hearing your opinion.

I'm no expert. Heck, I haven't been promoted to shoot-my-mouth-off, yet. ;) "Tenkan" is the turn to match the opponent's body direction, not the applied technique. You may lead the opponent into various directions using his inertia and "empty" spots at that time or you may apply a kokyunage, which has nothing to do with "centrifugal force" on the opponent. That's all I was saying.

FWIW

Mike

stuartjvnorton 03-21-2005 07:18 PM

Re: Tenkan and Centrifugal Force
 
lol, the power of the internet.
couldn't find one with shite swinging uke around though...
http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html

And here's one mentioning the "apparent" centrifugal force:
http://www.answers.com/topic/centripetal-force

Mike Sigman 03-21-2005 07:27 PM

Re: Tenkan and Centrifugal Force
 
Quote:

Stuart Norton wrote:
lol, the power of the internet.
couldn't find one with shite swinging uke around though...
http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html

And here's one mentioning the "apparent" centrifugal force:
http://www.answers.com/topic/centripetal-force

Here's the definition:

centrifugal force (sen-trif-yuh-guhl, sen-trif-uh-guhl)

A force that tends to move objects away from the center in a system undergoing circular motion. Centrifugal force keeps the water in a whirling bucket from spilling or throws a rider in a car against the door when the car goes around a sharp curve. Centrifugal force is actually a form of inertia.


Frankly, I can't see where it's worth my time to argue something that anyone with a basic physics background would just shrug and smile at. There is no "centrifugal force"... what you feel is an object attempting to maintain it's straight-line direction (Newton's First Law, I believe) while you try to contain it in rotational movement. That is not a force that requires a special name, as people mistakenly did for a while.... that is inertia at work. Should we rigorously derive the equations so there's no question?

Regards,

Mike Sigman

RonRagusa 03-21-2005 07:49 PM

Re: Tenkan and Centrifugal Force
 
Not all tenkan is done just to match uke's body direction. There are numerous techniques that use tenkan as part of the take down or projection of uke during the application of the technique. The tight circular motion executed by nage forces part of uke's body to assume a path with a greater radius; the part of uke's body being held by nage will travel a path more in line with nage's vector. Uke is therefore forced to reconcile the conflict where his single body must assume more than one vector and velocity simultaneously. Since acceleration is a function of velocity and direction, uke's body is accelerated at different rates all at once. The result is he is taken off balance and thrown.

Mike Sigman 03-21-2005 08:01 PM

Re: Tenkan and Centrifugal Force
 
Quote:

Ron Ragusa wrote:
Not all tenkan is done just to match uke's body direction. There are numerous techniques that use tenkan as part of the take down or projection of uke during the application of the technique. The tight circular motion executed by nage forces part of uke's body to assume a path with a greater radius; the part of uke's body being held by nage will travel a path more in line with nage's vector. Uke is therefore forced to reconcile the conflict where his single body must assume more than one vector and velocity simultaneously. Since acceleration is a function of velocity and direction, uke's body is accelerated at different rates all at once. The result is he is taken off balance and thrown.

Y'know... all you've got to say is that I'm wrong about using "tenkan" for instance with Sayu Nage and try to support it. Right now, looking at your statement above, it appears that the best you can come up with is that Tenkan is "part of" a number of throws. It's "part of" some forms of Sayu Nage and other throws and it does not necessarily involve what some people are calling "centrifugal force". "Tenkan" means "turn"... it doesn't mean "application of centrifugal force". Actually, I'm a little stunned that this could come up. No wonder some people don't want to define Aikido.

FWIW

Mike Sigman

Mike Sigman 03-21-2005 08:05 PM

Re: Tenkan and Centrifugal Force
 
Quote:

Rupert Atkinson wrote:
I firmly believe that centripetal and centrifugal forces can and should be developed. I have done it myself for ages and am constantly amazed at how weak at technique some people are, even after years of training.

Centripetal force is that what develops when you enter tenkan and draw uke in - sure you use his initial movement, and then add some, and the more you CAN add the more powerful your technique becomes. Centrifugal force is that which is used to spit uke off. Likewise, the more you CAN add, the more powerful your technique becomes.

You can, and should, develop this power.

I don't have a problem with developing the skills you're talking about, Rupert. What I have a problem with is the assertion that "Tenkan" by definition means the application of these forces. It means "turn". It is a form of entering an attack. You can enter an attack with tenkan and apply a kokyu nage without ever applying "centrifugal" or "centripetal" force.

FWIW

Mike Sigman

bendo 03-21-2005 08:12 PM

Re: Tenkan and Centrifugal Force
 
A person not trained in classical mechanics will not try to understand aikido via force vector...Perhaps you are both saying the same thing, just using different words???

RonRagusa 03-21-2005 08:14 PM

Re: Tenkan and Centrifugal Force
 
Forces arise from the relative motions of bodies. Tenkan is not an application of force it is a contributing factor in the generation of force.

RonRagusa 03-21-2005 08:15 PM

Re: Tenkan and Centrifugal Force
 
Quote:

Ben Walter wrote:
A person not trained in classical mechanics will not try to understand aikido via force vector...Perhaps you are both saying the same thing, just using different words???

In a way, the study of Aikido is training in classical mechanics; without all the math. :)

bendo 03-21-2005 08:24 PM

Re: Tenkan and Centrifugal Force
 
There would be cause for a dojo to open up spruking mathematical martial arts! -> part technique, part applied physics... You would have people just lining up waiting for the doors to open!

It is interesting that although a lot of poeple here acknowledge the physics side of aikido, i dont think that anyone has ever tried to rigoursly define aikido from this perspective. Imagine if the Xtreme MA animators had specialised on aikido only? I beleive that alot of debate about aikido principles could be settled this way...

On a side note, this XMA documentary (?) made a interesting remark concerning energy derived from the earth (or something along those lines)... they show via modelling that as the guy goes to strike his balance shifts creating an energy wave travelling up his leg and out his arm to his fist... i suppose more bang for you buck. I found this point extremly interesting from an aikido perspective! Got me thinking anyway!

Moses 03-21-2005 08:25 PM

Re: Tenkan and Centrifugal Force
 
quote" That's to say that there appears to be a power at work that's beyond the exertion of normal human strength." quote

I am still hung up on this, does this imply something extraordinary? Or just someone more talented than yourself? Can't it be stated, that those who possess talent beyond ourselves are are simply just talented? While being a lame analogy, wasn't Michael Jordan far beyond his peers, yet he possessed no special talents, i.e. no extraordinary talents? Rather as a basketball player, wasn't' he just gifted among his peers at that time?
Just a though, Moses Jenkins


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