Martial Arts Physics 101: Ch 1, Terms and Newton's Laws

[nianfong]

Thanks Ken! I'd like to invite you, Ken Fish, and/or Chris McKinley to also start an anatomy 101 thread for us to refer to, if you have time .

I think these physics primers will basically be:
Ch 1: basic terms, Newton's Laws, conservation of energy/momentum.
Ch 2: conservation of angular momentum, rotational mechanics (this will be the leverage and 4 oz moving 1000 lb chapter)
Ch 3: structures and flexible bodies, wave mechanics, fluid dynamics in human bodies (this will be the fajin chapter)

[cdobe]

Again, wikipedia's choice of words is imprecise, not to say wrong. I do understand the science behind this quite well and I also understand, that a lot of physicists and engineers talk in some kind of abbreviated language about these things. I hope that you will make an effort to understand my point as well. It is totally sufficient for all our purposes to talk about force, or specifically talk about its direction or magnitude. But in general, this is not what people on this board are talking about, when they use the word vector. Most often people talk about "paths" when they say vector. That's my motivation for arguing against the use of the term. It doesn't make any sense for our purposes.

[nianfong]

ohhh I see. I understand your point, but I think that using these physics terms correctly would help alleviate some misunderstandings that some people have been having when reading some of Chris Mckinley's posts (specifically, recently), but also other posts about mechanics of movement.

so back to topic, do people understand these basic terms and basic laws as I've laid them out, and how they apply to what we train in MA?

This is why we train our legs and hips because they are the largest muscles in the body, generating the most force. Also, all force comes from the earth, literally, because we must push off of the earth to generate momentum.

What this means is when we do our earth-shattering qi-powered fajin explosion, the instantaneous sinking of the body increases our friction with the earth, allowing us to push off of the earth with more force horizontally, so that our fists have more momentum and energy to draw from the earth.

This is also why for every one of our "perfect" punches to the front, we also have a backwards movement, to balance it, like for the classic shaolin/karate chambered straight punch. Pulling back the chambered fist generates backward momentum that balances the forward momentum of the punching fist.

For xingyi tiger form, our upper body pounces forward, but the lower back/waist/hip has to pull backwards to maintain balance.

gotta run. please read the chapter and think about it.

[Mello]

cdobe, are you talking about the difference between phenomena and the description of phenomena? If so, i agree. Vectors don't exist; they are descriptions of reality but not reality itself.

[Chris McKinley]

Fong,

The anatomy one will necessarily include far more information than the level of basic physics necessary to cover what we do. I would suggest an organized link page rather than a primer. By the time we're needing anatomy references, we're usually well into the details of a topic. I won't be able to tackle such a project till my computer is fixed. I'm on iPhone currently.

[G. Matthew Webb]

Yes definitely, I agree about an anatomy sticky. Do you want to write that? I think your anatomy knowledge is much more complete than my own. Perhaps Ken Delves, Ken Fish or the other more learned doctor types can also contribute.

Good idea about having an anatomy and a martial arts physics 101 stickies which should be a summation of the best of the threads, pruning away the many dead branches. I'm surprised that RSF does not have stickies that cover the usual territory that gets discussed repeatedly or of a particularly insightful discussion. If I'm mistaken and there are stickies somewhere on RSF, then please point me to them!

Matthew Webb

[Sean]

I love this thread! Thanks nianfong!

p.s Two very good books to help the layman understand this stuff are Richard Feynman's "The Nature of Physical Law" and "Six Easy Pieces".
http://www.amazon.com/Six-Easy-Pieces-Essentials-Explained/dp/0201408252

[Snork]

cdobe, are you talking about the difference between phenomena and the description of phenomena? If so, i agree. Vectors don't exist; they are descriptions of reality but not reality itself.

I'm sorry, but I disagree. Vectors do exist. If "vectorishness" wasn't a property of the space we inhabit, then mechanics and dynamics problems wouldn't be solvable through the help of vector maths. The key is this clever piece of argument judo by Fong:

cdobe, really the crux of my argument is this:
do you dispute that displacement is a real, and measurable vector in the real world?

This is pretty deep because the way in which distance is defined is the basis of how you define the space in general. The fact that we can get a ruler and get a repeatable, consistent measurements of distance wherever we are shows that the space we inhabit satisfies the properties of a Euclidian space. From there you can show that it is a vector space (showing that force and acceleration are vectors takes more work, but once you've got mass somewhere you've also got vectors.)

But vectors come with a lot of baggage, people tend to think that the common graphical representation of vectors, arrows, are vectors, but they are not really. And certainly there is no need to start proving vectors in any serious way.

[Pandrews1982]

This is why we train our legs and hips because they are the largest muscles in the body, generating the most force. Also, all force comes from the earth, literally, because we must push off of the earth to generate momentum.

What this means is when we do our earth-shattering qi-powered fajin explosion, the instantaneous sinking of the body increases our friction with the earth, allowing us to push off of the earth with more force horizontally, so that our fists have more momentum and energy to draw from the earth.

I disagree with this, not that this isn't a way to generate the striking force as you are explaining, but that you can generate said force in a different manner and it seems like you present your model as the only way to do this.

For example place a ball on a table then tip the table over, the ball is pushed forwards as a projectile and moves along an arc like path; there is no pressing force up from the base of the table propelling the ball outward.

Now similarly take a classical san-ti-shi posture, lift your front foot and let your mass shift forwards (from a central point in the torso, say the solar plexus), your rear foot is now simply a pivot point the rest of the body is essentially falling under the influence of gravity with your fist as the lead point just like the ball being propelled outward. When the lead foot touches the floor the rear foot steps up back into the classical san-ti-shi. The actual impact of the strike may be generated purely using the torque of the spine rather than wave from the floor, the movement of the body puts mass behind the strike to drive into the space of the opponent.

In such a model there is no emphasis on pushing off the ground, not saying it's not there but I am saying that the method is not as dependent upon the push against the ground to generate the force of the strike.

[nianfong]

a valid model, however, a good portion of the energy of the punch you describe still does come from the ground. It may be true that you don't emphasize the push off the ground with this type of strike, but when you pick up your front foot, your back foot is still pushing off the ground, if at least just to stay straight.

In your case you are using some of your own gravitational potential energy by "falling" forward (which originally came from pushing off the ground). If your case is the pi quan that I know, then that follow step actually requires your front foot to grip the ground, where you draw energy (actual physical energy) from to anchor the turning of your hip for the strike. If you did this pi quan on ice, you would probably find that the power you generate is much reduced because you basically are not using your legs to generate the power--only your core. Yes, you can get some power with just the core, but the quads and glutes are the largest muscles in the human body.

-Fong

[Pandrews1982]

Well, there is no distinct or at least no conscious/significant push into the ground from engaging the muscles to press down with the rear leg, any push from the ground is merely the reactionary force from holding the body mass on the rear leg.

The movement describes the basic step "Zhong" or advancing step and is critical in performing chicken stepping correctly, at least in the way which is used by my branch of xing yi and it can be utilised for any method though in basic training beng quan, pi quan and zuan quan are primarly used with this step. The strike would always occur in mid-step before the lead foot returns to the floor the follow step occurs after the strike is complete. The hip and shoulder rotate in opposite horizontal planes however this rotation is caused by twisting/untwisting from the back/spine area in the centre of the torso. I believe that the idea is actually just to generate the impactive portion of the strike using the core but to back this up with the continued forward movement of the body mass to drive through the opponent.

Whether this tends to reduce the potential power generation or not i don't know so far it's been enough power for my needs and have trained with a number of people who have noted the heaviness of our kind of striking.

I've also noted another type of power generation in bajiquan which seems to use a type of dropping of the body mass in place to create an outward force rather than the press through the ground kind of method.

[GrahamB]

Paul makes a good point - sinking and pushing of the ground is not the only way to punch. Torquing the spine for most of the power provides plenty of oomph. You can also use this method for punching while in the air - say delivering 3 separate punches as you jump at somebody.


I think there's also a correlation with MMA fighters who charge down the opponent with punches - the first one is powered from a push off the ground but subsequent ones are more from spinal torque - I'm thinking of Machida when he got a few hits in against Jon Jones in his last fight before getting choked out.

[nianfong]

Yes definitely, I agree about an anatomy sticky. Do you want to write that? I think your anatomy knowledge is much more complete than my own. Perhaps Ken Delves, Ken Fish or the other more learned doctor types can also contribute.

Good idea about having an anatomy and a martial arts physics 101 stickies which should be a summation of the best of the threads, pruning away the many dead branches. I'm surprised that RSF does not have stickies that cover the usual territory that gets discussed repeatedly or of a particularly insightful discussion. If I'm mistaken and there are stickies somewhere on RSF, then please point me to them!

Matthew Webb

according to Felipe, back in the way old days, they tried making a "hall of fame" section, but it didn't work because not enough threads went into it. I think we may want to, instead, make a reference/FAQ section, for people to refer to.

[KEND]

The method of generating 'jing' is one of many. It should be possible to generate five element shock power while sitting with feet off of the ground

[Wanderingdragon]

This is not even physics 101 'its common sense you will generate no power without some connection to the ground, in a chair with your feet off the ground the chair is still connected to you and the ground. If you are flying through the air the leap you took is your power generation is the leap you took off the ground, if you hit something hard enough you will push yourself backwards if you not touching the ground, no amount of torqueinv will change that.