Newtonian mechanics and Punching

[Hermit]

What about the seeming trade-off between dize and speed? I've often noticed that people who gain a lot of muscle mass often lose speed.

Anton, gaining muscle does not equal to losing speed. Thats just a myth. You can gain muscle and increase speed if you train correctly (i know i did).

Also, if a fighter is twice as big as you, that does not mean that his arm (the object that has momentum during a punch) is twice as heavy as your arm... So the payoff for having increased mass under this admittedly limited model is arguable.

The momentum does not come from the arm alone. Read a previous post describing a stepping punch. Also, twisting movement of the torse adds momentum (which is higher when the body has larger mass), although this wasn't in the model.

[CFT]

In terms of adding a twist about your centre-line in order to add impetus to your punch:

(1) Angular momentum L = I x w
where I = moment of inertia
and w = angular velocity

This is similar to the formula for linear momentum:

(2) Linear momentum p = m x v
where m = mass
and v = linear velocity

The rotational kinetic energy, Er = 1/2 x I x w2 (w-squared)
Similar to linear kinetic energy, El = 1/2 x m x v2 (v-squared)

So the faster we can twist or the larger the moment of inertia the more momentum or energy we can deliver to the opponent. As my critics like to point out ..... bleedin' obvious innit? Yep 'fraid so!

Heard of the Law of Conservation of Angular Momentum? If you've seen figure skater on TV, when they do the final spin in their routines. They start turning with their arms out, and as they draw their arms in they start to spin faster.

When they draw their arms in they are reducing their moment of inertia; since their angular momentum is conserved (bar friction) this means that their rotational velocity must increase.

I don't really think this is what we do when we swivel and punch, but you can see that there is a mathematical description for the energies involved.

Moment of inertia, I, for the torso is something like: 1/2 x M x R2
where M is the body mass and R is the distance from the centre line to the shoulder. Assuming the WC practioner is a cylindrical mass or dummy!!

Look here for some pictures of common shapes and their moments of inertia:
http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html#cmi

As you can see this very simplistic model just assumes that we're solid rods or blocks. Nothing like a real anatomical model to take into account musculature and tendons.

So my advice is to spin round and round really fast, creating a path of destruction wherever you go

[YongChun]

Along this line, there was a Canadian study done once by a group of scientists that tested the natives up North (used to be called Eskimos but now are called Inuits). Anyway after extensive aptitude and IQ testing the report was written up that concluded that these people did not have the intelligence nor aptitude to deal with the harse Winters in the North and survive. Well obviously they have been doing it for hundreds of years. So point was that these kinds of tests were often quite useless.

Often as in the Bee example the mathematical model is not representative of the thing being modeled. There was also a study done a long time ago that trains can never go faster than 30 miles an hour. Why? Well when a train goes so fast like that, all the oxygen will get sucked out of the train and then everyone will suffocate to death.

Originally posted by CFT
That's a good story and underlines the problem of oversimplifying the problem. The "model" that proves the bumble bee cannot fly assumes that the bee flies in a fixed wing mode, like an aeroplane. Therefore given it's wing size, it was calculated that it couldn't possibly generate enough lift, and therefore couldn't fly. Obviously nonsense!!

Subsequently, scientists have discovered that the bee's wing actually moves in a more complex figure-of-eight pattern and I think that it can generate lift in both the down- and upward-stroke (if I remember correctly).

Obviously mathematics is no substitute for practice, but sometimes mathematical models provide us with insights that are counter-intuitive. Many modern athletes and sportsmen/women make use of the techniques of bio-mechanics and sports science in order to improve their performance. Obviously they have to train and practice as well.

[yuanfen]

Hi Ray- good post on the issue of whther the model is appropriate for the study.
Regarding Inuit-
Alaskan Malamutes evolved out of the the AKC recognition-their roots (including mine) are in the Inuit world and the Inuit dog. In a book on studying the intelligence of dogs -malamutes were ranked lower than border collies or poodles. If one looks at the criteria used---
the dogs that performed the specified tasks-usually obedience oriented were ranked higher- the malamute world does not rank obedience as an important value... but creative survival in 70 below zer0 50 mph winds per Adm. Scott's Antartic expeditions?... a malamute is a creative survivor-
so also in the Arctic.

The Inuit and their dogs had the appropriate intelligence to a high degree in their environment.

If you change the function- you can geta different result- the border collie for herding sheep, the poodle for circus tricks and the
hybrid alaskan husky for competitive racing (Iditarod).
Then there are training and adaptation variables- but that's a different story.

In science- before going to the equations- appropriate analysis of the nature of the problem- is a key step.

[Andrew Williams]

For me, and I speak only of myself, the example presented and its use of formulae, though entertaining, is too limited to be of any real use. When considering any human movement, Theory and Formulae need be considered with much physiological understanding.

I would also suggest that even if we were given enough time and space to consider and calculated the forces involved, in say punching me in the face, we could still not calculate my reaction to it. Though some may believe they could, star fish.

Many moons ago I gave KJ a list of things that need be considered in the punching action/reaction. I think, though incomplete, it was very lengthy and detailed. I will search my old tombs and perhaps if I can find it I will post it here, if you are interested.

I enjoy math, I enjoy physics use of it, but math without physiology and psychology it leads to understanding the ball bounced but not the bouncer.

Cheers guys Andrew Williams

[PaulH]

Have we in world but time and space, I would love to read that long lost post of yours. Thanks, Andrew W.

Cheers,

PH

[Phil Redmond]

Tests similar to the Canadian one were also done here in the States to show certain ethnic groups were inferior. These test are now looked upon as biased and flawed.

[kj]

Hi Andrew,

Originally posted by Andrew Williams
Many moons ago I gave KJ a list of things that need be considered in the punching action/reaction. I think, though incomplete, it was very lengthy and detailed. I will search my old tombs and perhaps if I can find it I will post it here, if you are interested.

We have a long holiday weekend coming up. Assuming our families leave us a little discretionary time, I'll aim to sort through my archives for the list you mentioned.

Regards,
- kj

P.S. Happy Thanksgiving, to all who celebrate.

[Andrew Williams]

“We have a long holiday weekend coming up. Assuming our families leave us a little discretionary time, I'll aim to sort through my archives for the list you mentioned.
Regards,
- kj
P.S. Happy Thanksgiving, to all who celebrate.”
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Hi Kathy Jo.

Have a fun long weekend, hope you have better luck than I.