• Archive through August 28, 2003 August 28 - 05:21 pm [20]

• Archive through September 01, 2003 September 01 - 02:00 pm [20]

thanks, tim. makes sense.

Yes, elasticity is 'yielding', more specifically it refers to the ability of something to 'recover' its form after 'deforming' forces (compressing stretching) are removed. This deformation (strain) is proportional to force (stress) applied until a limit is reached, after which any additional stress will leave it permanently 'deformed' (Hookes Law or more commonly known now as Bob #2's Twig Law).

Hysteresis is a lag in the application or removal of a stress, repeated stresses of VARYING forces or the inherent nature of the material (varying degrees of elasticity) itself may mean that it doesn't fully regain it's original shape/dimensions and sets up its own action and reaction forces which leads to energy loss (inefficiency) called Hysteresis Loss and less predictable (more comlicated) overall behaviour. The inefficiency of walking in sand is an extreme example of hysteresis loss.

If you want to understand how airpressure can effect mechanical efficiency, think about what you do with regards to breathing when you want to lift a heavy object from the floor.

Waves travel in different ways and can interact subtracting (interference) or adding (reinforcement) effects with respect to each other. All you need to create them is an object to vibrate (oscillate) and a medium to 'carry' them. Different objects vibrate in different ways producing varying periods, frequencies and amplitudes and travel in different mediums with varying degrees of success or not at all.

The human body is composed of material in layers of differing density and elasticity. It also has large and small cavities (gaps) which can expand and contract as well as being composed of alot of water. It is a difficult matter to understand how it is going to react from a purely 'physical' aspect. Simple solid body models are good for simple actions, but i don't think they're that useful for more complex interactions. That is of course without taking into account as Bob #2 pointed out the physiological and neurological aspects and the interactions between them.

Anyway none of this affects your ability to do martial arts or even understand them may even inhibit it.

thanks, chris, for taking the time for such a complete/technical answer. makes me wonder if you are an engineer. there are some neat terms, even if the theory of such things doesn't help you do it--"hysteresis loss" for example.

anyway, yielding, compression (breath or tissues), wave, etc., is all stuff we do (either by intuition or training)...but being the antithesis of a science type, i get morbidly curious about the science of it, sometimes.

i am glad bob#2 is around to provide us all with the graphic examples: injured twigs, and damaged old women. now if i'd been given examples like that in highschool physics, i might have paid attention.

best to you...

I like to give my bag the ol' two finger pinch and roll, tug on it a little and maybe give it a light slap, but when a really let loose and whack it, I get a quesy feeling in my stomach and my knees buckle. Am I doing something wrong? Also, I'm not real clear on proper posture and alignment. When I'm hitting my bag, I've got one foot up on the counter and I'm leaning forward. Is that correct?
Just out of curiosity, how do you guys with 80 lb. bags manage? My bag's pretty heavy too, but it sure as hell aint 80 lbs.

Ned,

Sounds like you're into some pretty serious practice. Can you go into more detail?

Of course your are doing something wrong, and the weak knees and queezy stomach suggest that you are not as ignorant of your actions as you profess (guilt catches up with us all). Despite your posturing you can't get away from the fact it is morally repugnant to pound underweight ol' bags whatever your political or social leanings/alignment, less than eighty pounds geez...

Ned,
Try wrapping your hands and using the proper lubrication.

duct tape!!! heavy bags. my dick is getting hard. ron, please remove my comment or move it to another thread.

willard

Helpful,
I'm just talking about hitting my bag like other folks on this thread. You must be a little slow.
Chris,
Since I've become a Jehova's Witness my feelings of guilt get are no longer relevant as I am no longer responsible for my actions. The only thing that matters now is that in the end, no matter what I do or how I act, I will be one of the chosen few and the rest of you will burn in eternal torment.
Tim,
thanks for the tips. I'm still having the same problems, but I am building up some endurance. I can hit it much harder and longer before my knees completely give out.
With all the abuse my bag seems to be swelling and getting heavier. Since none of you big bagged bastards wanted to share your secrets on how to manage an eighty pounder, I went through all the previous posts and figured it out. They're supported by chains! I'm seeing the doc tomorrow about surgically implanted d-rings.

extingushing candles with a punch? bah! thats elementary, try extinguishing your fireplace, NOW THATS THE GIFT OF CHI POWER!!!