Uechi-Ryu.com

Ha Ha!
Hey Bronze, you're right.

Reminds of the "musicologists" who thought they could analyze Beatles records to the point where THEY could write another "Hey Jude"!

It's fun though, and I find it interesting to look at the physics of Karate since Physics and Karate are two of my major interests!

And, that formula IS misused 99.9% of the time.

NM

_________________
The music spoke to me. I felt compelled to answer.

Good post Neil and here is some discussion from Rick B. He is also looking for some stuff he wrote on Kinetic energy.


“Before I respond to your excellent post, which I am by no means rebutting, I would like to point out a common error that a lot of people make when applying physics formulae.

The formula "F=ma" (Force = Mass * Acceleration) is NOT USED to calculate the force DELIVERED by the accelerated object, nor the
kinetic energy it accumulates by being accelerated. The formula F=ma is used to calculate the FORCE REQUIRED TO ACCELERATE the MASS.”


Rick Bottomley: Acceleration is = Dv/ Dt or change of velocity with respect to the time taken to affect that change. Note: Dv is not sign dependent, it can apply to an increase in velocity as well to a decrease in velocity. Therefore, it can also be used to calculate the force to de-accelerate a body in motion and in the case of a strike, the target body has to absorb that amount of force to bring the strike to a rest condition.

Also, I like to use the force equation because it helps to explain one of our principles; "to land on the weapon", which relies on the acceleration of gravity to generate additional force when we deliver a blow in this manner. I don't think I am applying it wrong in this application or bathroom scales wouldn't work.


“Take your train analogy for example. The train has a mass of "x". You want to accelerate it at a rate of "a-per z's" The formula tells you how much FORCE is REQUIRED to get it going there, not how much energy it will carry due to its movement.”


Rick Bottomley: It tells you exactly how much force is required to stop it or how much force the train will deliver to an object before coming to a rest


“This is one of the most often-quoted and most-misunderstood formula of all time.Incidentally it is known formally as Newton's Second Law of Motion, which you can look up in any high school text if you wish to verify this.”


Rick Bottomley: I believe that I am applying the force equation correctly


“A better formula for your purpose is K= (1/2) mv2 "KINETIC ENERGY= 1/2 of the MASS, times the SQUARE of the VELOCITY.

It is kinetic energy that a moving object delivers when it hits something. Velocity is easier to use in calculations because it is a constant speed, not a rate of change, as is acceleration. Note that the formula immediately discards one half of the mass.

Unit of ENERGY": joule. (1 joule is the energy needed to push with a force of one Newton over a distance of one meter.)

Unit of FORCE: Newton: The force it REQUIRES to accelerate one kilogram from rest to a VELOCITY of meter/secon, in one second's time.”


Rick Bottomley: Kinetic energy is an excellent formula to use a tool to improve the effectiveness of ones blows or strikes. I don't use this principle in a karate setting as most people don't have an intuitive feeling or understanding for "energy" (joules).



Good discussion folks.

I'll be taking physics next spring... after calc 1.

*sigh* this stuff is killing me.. i'm too old for this crap.

Or you could just hit each other and see what hurts !!!!

cause the math makes my head hurt .... reverse punch Kiai !!!!!

Hey: we're WAY past the Karate now!

Anyway...F=ma is commonly used to point out to students "the faster your strike is going, the more damage it will do."
Of course that's true, but F=ma is not the formula that proves it.
It's like saying" I can prove the world is round: Pi R Sq!

Right concept, wrong proof.
********************************************

Only the brave of heart need follow along:

Acceleration REQUIRES force. It CONSUMES it. It does not PRODUCE it.
This force is CONVERTED to potential energy in the MASS, in the form of VELOCITY. (steady-state speed in one direction.)

When MASS hits target, the potential energy is converted back to impact ENERGY and guess what? It's EXACTLY the same amount consumed in the ACCELERATION.
20 pounds in, 20 pounds out.
100 pounds in , 100 pounds out.

It makes NO DIFFERENCE if it took 10 seconds or 100 years: the SAME MASS travelling at the SAME VELOCITY has the SAME IMPACT ENERGY.

The acceleration phase is where the energy was CONSUMED or CONVERTED, not where it was "DELIVERED".

We're in space.
We see two spaceships of exactly 1000 lb (mass) travelling at exactly the same velocity.
One has a huge engine and got up to this velocity in a few minutes.
The other has 1/10th the engine so took ten times longer in getting up to (accelerating) to this velocity.
When they both hit a planet, they have EXACTLY THE SAME impact energy.

IMPACT ENERGY is contained only in VELOCITY and MASS, NOT acceleration.
This is why F=ma does not apply. Acceleration CONSUMES the force.

The slow 12lb haymaker and the fast 12lb Karate shot have EXACTLY the same IMPACT ENERGY, provided their impact velocity is the same and their mass is the same.
**********************************************************
"Also, I like to use the force equation because it helps to explain one of our principles; "to land on the weapon", which relies on the acceleration of gravity to generate additional force when we deliver a blow in this manner. I don't think I am applying it wrong in this application or bathroom scales wouldn't work."--Rick B.
----------------------
As you can now hopefully see, the force equation does not support or "explain" this (correct) principle. Right concept, wrong formula.
Of course exploiting gravity adds to acceleration, but still: 20 +5 in, 20 + 5 out. NM
***"********************************************
"“Take your train analogy for example. The train has a mass of "x". You want to accelerate it at a rate of "a-per z's" The formula tells you how much FORCE is REQUIRED to get it going there, not how much energy it will carry due to its movement.”


Rick Bottomley: It tells you exactly how much force is required to stop it or how much force the train will deliver to an object before coming to a rest

-----------------------------------------------
YES! EXACTLY same in/same out. 100 lb in , 100 lb out. No extra magic power or "energy" from "acceleration". This is my point.
NM
***********************************************************

"“This is one of the most often-quoted and most-misunderstood formula of all time.Incidentally it is known formally as Newton's Second Law of Motion, which you can look up in any high school text if you wish to verify this.”


Rick Bottomley: I believe that I am applying the force equation correctly"
----------------------------------------------------------------------------

You are NOT applying it correctly if you are using it to demonstrate that a fast-moving strike carries more impact energy than a slow moving strike, although this principle is true. F=ma is NOT the formula that proves it.

You need the formula which converts VELOCITY and MASS to ENERGY, which I provided in an earlier post. Acceleration (the "a" in "F=ma") does just the opposite. It CONSUMES energy.
**********************************************************

"Rick Bottomley: Kinetic energy is an excellent formula to use a tool to improve the effectiveness of ones blows or strikes. I don't use this principle in a karate setting as most people don't have an intuitive feeling or understanding for "energy" (joules)."

Thank you. This is my point.
They WILL have an intuitive feeling and understanding if you "transfer a few joules" into them with a high VELOCITY strike, as my teacher has done on so many occasions, painfully proving the concept with no faulty math required.

NM

_________________
The music spoke to me. I felt compelled to answer.

“You are NOT applying it correctly if you are using it to demonstrate that a fast-moving strike carries more impact energy than a slow moving strike, although this principle is true. F=ma is NOT the formula that proves it.”

Ummm the usage of it was to illuminate that very thing.

I'll let Rick B reply the rest. (I get lost in the math. )

So aside from the math...

Impacts only happen when the mass is accelerated prior to contact.. Right?

The rate of acceleration does not effect the amount of energy stored in the mass, since it is only relative to the velocity.. Right?

But the rate of acceleration will change how quickly the energy is transferred to the mass. Right?

So, the faster we can accelerate (use all the joints) the more energy we can transfer to the mass (use of body alignment) in the shortest time = small space..

So you still need some space between weapon and target in order to take advantage of impact force transfer. This does not mean that you cannot transfer energy to the target without space but rather, space = time for energy to be stored in the mass for release in impact and not using any available space to store energy would be a waste if indeed the goal was the generate maximum force.

Being in contact prior to energy generation and release means no storage of energy in the mass, thus less total energy transfer and energy is only transferred to the target as fast as it can be made. Interesting then because all the joints must move exactly in unison to minmize time of total energy transfer in order to maximize an explosive fajing push OR strike.. Essentially for either you need all energy engines to turn on at once, transfer to aligned mass, and then turn off; This it seems rather than a progressive activation of the joints..

_________________
Shaolin
M Y V T K F
"Receive what comes, stay with what goes, upon loss of contact attack the line" – The Kuen Kuit

Example:
A shoken delivered is accelerating and reaches its target with still more ability to produce speed but of course is slowed and eventually stoped by meeting flesh or lenght of arm.
The arm is still in the process of using the energy given by your body to send the object (shoken) on its way.
...This energy is added to the impact force instead of the energy required to accelerate the arm is it not?
... Energy is used to recoil from the strike as well unless you decide to add time on target. How much energy is worth draining into the target before recoil I often wonder, best bang for my buck

I`m thinking my arm is the train and the faster the train goes should create more damage after impact, but the "train" is linked to the body which is the engine of the train and if that engine is moving forward as well as fueling the train for constant acceleration how can we create a formula? Can the force of the impact be accurately measured?
Would be interesting to have a test dummy (not me ) to measure the forces at different points inside the body not just surface impact.
...Will not greater speed increase the "shock wave" effect to the target?
I kept away from the math (I do understand the formula`s posted somewhat) as I have nothing to add to that area but i do have questions fueled by imagination.

_________________
Léo

This is just my take..



Yes it is, BUT we're talking fajing - body power, so not only is the shoken accelerating but so are all the component parts or joints of the body.. Think of the body as a balloon with all parts expanding at once, a body explosion, where the ‘fist’ is merely the release or focus point of all the energy, but it must be connected.



Not if this is done correctly. The example is a bullet.. Take a live shell and hit the cap..BANG! What happens? The power charge burns generating energy, this energy is transferred to the mass, the bullet and the bullet shoots out of the shell casing. Once the powder burns and ejects the mass all energy possible was made and transferred to the mass.. In the same way the idea in fajing is to fire all the muscles in the body at once to drive the aligned joints in a very short period of time = short power and then shut off at the end of their <joint> ranges. So if the strike is a 3 inch strike then the idea is to have made <expansion> and transferred all this energy in the three inches before the impact happens.. In this case the body having released all possible energy has no more to put into the mass is relaxed <compression> and resets for the next fire. The shorter the expansion and compression the faster the cycle can complete and repeat, this is determined by the structure and mechanics used..



The energy that accelerates the connected body mass <where it is stored> is the same energy that is then released from the connected body mass into the target.



Only if there is no impact.. Or in technical terms: You missed and hit air.. Retraction is passive, unless you need to retract just a tad to make space but if you train energy issuing you are always making space with structure...




Not worth a cent. Because any additional slow energy drain <a push> will rob you of valuable time that could have been used to reload and fire again. Best to keep the cycle moving at a quick and efficient pace for a stream of power bursts..

Pushing at the end of the strike will:

Use the remaining joint power for a last minute push instead of including it in the Bang.
Waste time that could be better used for reloading.
Limit the ballistic nature of the release, impact and reload.
Increase the chances of hyper extending the elbow joint..
Make you stiff, slow and ruin your flow.

All for a little push at the end of what should be total body explosion. This is not fajing..

_________________
Shaolin
M Y V T K F
"Receive what comes, stay with what goes, upon loss of contact attack the line" – The Kuen Kuit

Jim:
You have put your finger on the center of the issue, as I did privately to another individual.
Isolating a single limb is folly and makes the formula, which is already the wrong one, even more impossible to apply in the application of a body-connected strike.

One would have to literally rip off their limb and somehow accelerate it, independent of the body, for even the *wrong* formulae to be employed in calculating the impact power of just this single, dismembered limb.

This is patently ridiculous, misleading, inapplicable and frankly embarrassing to anyone who has even a faint high-school grasp of Newtonian physics, which by the way, are being erroneously employed to "illuminate the concept".

Any wonder students roll their eyes.

NM

_________________
The music spoke to me. I felt compelled to answer.

What is Fajing?

Physics isn't the answer to karate.

The answer is practice.

Tony:

You can not make anything work without putting the work into it so yes practice is indeed what you need.

But smart practice does not hurt either. Trying to figure out how to hit harder is needed. IMNSHO And then, yes, step into a conditioning circle or ring and see if your ideas on how to hit harder actually work or are just BS.

So having Rick B explain the physics to me has helped me hit harder because the methods he uses exemplify what is needed to hit harder and I can translate his explanations into an actual strike.

Of course just smacking people a lot helps too.

Tony, physics in karate is for when no one is attacking...like taking a gun apart to see how it works...BUT can you shoot?




Sorry some embarss you Neil, not all MA regarless of ability grasp Newtonian physics or see the importance of it I find that amussing, not offended as High school was the best time of my life without indulging in "Newtonism".


Because the instructor doesn`t understand basic physics?
Application of MA concepts are difficult to explain at best of times, learning curve for all.





I understand that Jim, as you see below quote from my last post. The energy supplied is unknown and I think unlikely to be delivered in a single burst or bang. I think it will still be accelerating when it meets the target, I know we disagree on this point as I`m not convinced that all enegy can be drained from the body in releasing a strike as then it would be at it`s end point and must recoil (better than lock at end point). On contact yes, it seems more likely as there is nothing to left to accelerate...it essentually places all the energy into the person struck and he/she has to deal with it.
Very interesting thread and one worth following, I`m learning but of course also debating.

_________________
Léo

Yes the amount is unknown..



Well this is the whole idea of fajing and short power, you are trying to release or transfer all the energy to the connected mass in the shortest time.

Do you train short power? Like hitting your partner with your fist or hand only a few inches away? Ever see Bruce in that old interview demo the punch.? Note the travel in the punch, the travel or distance of the punch was very short and not the point, it was the velocity and connectedness in the short travel distance of the strike.

Let me repeat: The velocity and connectedness <before and during impact> is what this is all about!

This relates to short power, you only have that short space to make the transfer, unlike with say a reverse punch that has a long length of expansion and therefore time to transfer energy.



Well it will not be accelerating AFTER it meets the target, but it could be accelerating up until it meets the target.. But the cycle should be near complete at this point and at least the way we teach the WCK striking the muscles need to shut off meaning that pushing the strike after impact is not correct or desirable.



The idea here is that energy transferred after contact is not useful since by definition it cannot be transferred to the accelerating mass for impact since impact has already happened. The idea of a strike vs. a push.. or a strike and then a push.



In the air the strikes <punching air or missing> we train the muscles to shut off before full extension of the arm or elbow joint. The bicep is not used at all and the ligaments stop the punch at the end of travel.



This is all true but I do not see what your point is..

The idea is that any energy left after the connected mass strike makes the impact is not going to increase the impact force, nor will a "push" at the end of the strike do much in the way of increasing damage since it is very much a last minute push.

So yes full extension and power transfer may not be complete on impact but the energy push trailer isn't what's doing the damage as there is no accelerating connected mass to transfer this energy to after impact.

_________________
Shaolin
M Y V T K F
"Receive what comes, stay with what goes, upon loss of contact attack the line" – The Kuen Kuit

Sorry, folks I just forwarded Neil’s comments on to Rick B now, he might reply. My fault I just got busy.

Rick B says in his world the practical reigns supreme so he looks at what works.

If he drops a weight onto a plate that can register the force it hits with, then guess what -- it will equal the force calculated in the formula commonly used by martial artists.

So for the practical I can hit harder purpose, the formula does give the right practical information.