The Nature of Force

[Wanderingdragon]

While training this morning , I started playing with some certain techniques , and it started me to wondering.
Is centripetal force ever a substantial force ?
Any thoughts ?

[neijia_boxer]

The large swinging backfists especially in Hung gar and other southern fists use alot of centripetal force. when you get hit by one it hurts. I say yes it is substantial.

[Darth Rock&Roll]

stone on a rope.

[Dmitri]

I'm sorry but both of those examples have nothing at all to do with centripetal force... That's just speed and mass. (Momentum, etc.)

Centripetal force as generated by rotating a human body is NOT substantial at all.

(Then again, I ain't no physicist so I may be wrong... it's been a long time since I studied anything about physics...)

[DeusTrismegistus]

Centripetal force is the force required to stay in circular motion and is a force toward the center of the circle. So when doing swinging techniques the centripetal force is the being directed toward the center of your body, so it can't be transferred into an opponent, or bag.

Swinging techniques derive their power from increased speed. If I Have a circle at the edge of my shoulders with a radius of one foot the circumference is 6.28 feet. If I rotate my shouders to complete the circle in 1 second my shoulder has a velocity of 6.28 feet per second. If I rotate my shoulders at the same speed but have my arm extended and my arm is 2 feet long the circle inscribed by my fist would have a circumference of 2*3*3.14=18.84 feet but would navigate the larger circle in the same amount of time, thus traveling at 18.84 feet per second and three times faster and three times the momentum.

Now the force required to move the shoulders at 1 revolution per second with the arms in will be less than the force required to move the same 1 revolution per second with the arms extended. If you are on a spinning chair you can test this yourself. Have someone spin you with your arms outstretched. When you bring them in you will rotate faster (think of figure skaters), when you extend them out you will slow down again. This is because the force is constant.

[Wanderingdragon]

Simply stated, centrifugal is force moving away from the center , centripetal is force moving towards the center. In Hsing I these forces move together, as with any circular motion i wouldsuppose. I have been working with the idea in Hsing I of being able to glue an opponent to the ground with centripetal force while striking with the opposite force, to me these forces as one piece are substantial, I don't know. In some of the other stuff I do there is much shocking , which also involves the use of centripetal force, forcing an opponents energy into the ground, with the ability to cause some serious whiplash, again I am curious as to whether or not this would be considered substantial.

[Dmitri]

I think I see what you mean, but the term 'centripetal' seems incorrect here IMHO. (Again I'm know very little of physics, so please correct me if I'm wrong.)
IIRC it's not a "real" force, because it doesn't really affect the object that's moving in a circle; it only affects whatever it is the object is attached to, i.e. the (inside of the) rope in Darth's example -- not the stone, or the (inside of the) arm in neijia_boxer's example -- not the fist.

The "real" force that is "felt" by the rotating object is the centrifugal one, but that, again, is not what is used to do the damage IMHO. These forces are only there because the object is attached. The "damage" is done via the object's velocity and mass.

[DeusTrismegistus]

Centrifugal force is not a real force it is just convenient to think of it that way because that is the feeling of being an object travelling in the circle. Like a kid on the merry go round. The object or whatever keeps the object from going off on the tangent (when you let go of a spinning stone on a string it will launch at an angle tangent to the circle at the point of release, which is a straight line and it will not travel outward) provides the centripetal force to keep it moving in the cirlce. For the stone and string its force from tension, for a car its force from friction from the tires and the road.

I really have no idea how you could glue an opponent to the ground with centripetal force short of smashing him on the head, or how you could strike with centrifugal force, which isn't real and is only the perception of the "equal and opposite reaction" of the centripetal force.

This is really why I don't try to examine martial arts in terms of physics. In most cases the systems are too complex for the average person to understand and the average person has at best a poor conception of kinematics and many misconceptions.

Also the term substantial hasn't been defined in how you are using it.

sub⋅stan⋅tial   /səbˈstænʃəl/ Show Spelled Pronunciation [suhb-stan-shuhl] Show IPA
–adjective 1. of ample or considerable amount, quantity, size, etc.: a substantial sum of money.
2. of a corporeal or material nature; tangible; real.
3. of solid character or quality; firm, stout, or strong: a substantial physique.
4. basic or essential; fundamental: two stories in substantial agreement.
5. wealthy or influential: one of the substantial men of the town.
6. of real worth, value, or effect: substantial reasons.
7. pertaining to the substance, matter, or material of a thing.
8. of or pertaining to the essence of a thing; essential, material, or important.
9. being a substance; having independent existence.
10. Philosophy. pertaining to or of the nature of substance rather than an accident or attribute.

The first definition would seem to apply and I cannot fathom how centripetal or centrifugal force can be used in a martial context. Quite simply the force is being applied at an angle that will make it impossible to effect the opponent.

[JusticeZero]

Centrifugal is useful for a number of throwing techniques, as it is how one sends the victim flying away at the end of being spun around and over the practitioner's center body mass.

[Wanderingdragon]

Deus, I respect your opinion , true no physisist am I , But to not try to under martial arts on a physical level is simply to stay at a physical level. No matter how inane one would consider a subject , to explore the bounderies , to try and understand the realities is the nature of art. When step off of the last step too hard and you feel it all the way at the base of your skull, or you throw your back out because of it ,this is what I mean when I say glue someone to the ground. There is a definite downward force in a whirlpool as much as there is an outward force and the greater the mass the greater the force , this is simpleton physics, but it is true.

[DeusTrismegistus]

Wanderingdragon, I am just not of the opinion that you need to understand the physics of martial arts. I really think that approach will hinder most people, especially at first. You may have enough experience that this is not the case. Either way I hope the explanation of the force helps you better understand whatever it is you are trying to explore.

[Wanderingdragon]

I guess you could be in the fact that this tract could be confusing to some, as it is a bit abstract, yet it is what is internal I believe. I will study the nature of these forces, further.

[DeusTrismegistus]

You know it seems like you are experiencing these forces and then trying to describe them with a physics term that closely resembles the feeling. That may actually make things harder to understand though. If you are able to describe what exactly the force you are exploring does, or how you are using it without assigning it a name that has accociations already assigned to it then we might make more progress in studying its nature. Just an idea.

[chimerical tortoise]

Hmm. I'm not a physicist but looking at the diagram on wiki it seems that centrifugal force is quite important:

circle centre = shoulder
radius of circle = length of arm to elbow
point on circumference = elbow
movement vector = forearm

One approach to short range power is through this way, in "inch power" it's not the inch that the wrist or even forearm travels, but the shoulder rotation that centrifuges the elbow, hence while it looks like you don't have much room, you actually are creating movement from the fixed centre and not just pushing a straight line. Seen/felt it done/explained, can't do it myself.

Regarding using physics to describe it, VT people always use analogies of car wheels and shopping trolleys, if it helps explain what you do then why not? For my straight punch I visualise Jupiter's solar orbit and use that to accelerate my mind in a physiological continuum before applying the Law of Sines and praying that my opponent's face suffers from Murphy's Law...

[Josealb]

WonderingD, you should pm Ken Delves about it, if you're really into the physics of the fists. He wrote a whole book on it. His User name is KEND.

He doesnt post much, but the last time he did he made short articles regarding this subject. In case you missed them:
http://rumsoakedfist.org/viewtopic.php?f=3&t=3743&st=0&sk=t&sd=a