Punching with as much energy as an M16 Rifle Bullet

[Melau]

To understand the destructive force of a well trained punch, it is necessary to compare it to similar occurences when talking about the resulting amount of kinetic energy.

In short, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.

In this example, it would be the acceleration of a gyaku-tsuki from a basic kihon stance. It accumelates a certain amount of energy during execution of the technique and transfers this kinetic energy on the moment of impact.

I was curious what a gyaku-tsuki could be compared to. Given the formula of E(k) = .5 * m * v^2 (where v is in m / s) I came to the following calculation.

m = 60 kg (this indicates that someone was able to put 60 kg of mass behind the punch. I do not know it his is an accurate guess, but a trained karateka can put a considerable amount of weight behind a fist due to utilisation of the entire body)

v = I got this from the following article http://www.sciencedirect.com/science/article/pii/S1877042814017571) which calculated the speed of a karate punch in correlation with Plantar Pressure.

E(k) = .5 * 60 * 8.23 (which is around 30 kph) = 2032 J, so 2kJ (rounded).

This is comparable to a M16 rifle bullet (5.56x45mm NATO M855, 4.1 g fired at 930 m/s) according to http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy). Naturally, because the kinetic energy is distributed across a far larger area (the fist) than the point of a bullet, it does not have the penetrating force of said bullet. Still, if one were to hit with purely the first 2 knucles of the fist, the amount of 'penetrating power' would still be something to be afraid of.

Please feel free to provide feedback, be it in my understanding of physics, use of sources / data or otherwise.

[bushido_man96]

I don't by the comparison with the kinetic energy of a bullet. Bullet's velocity is measured in feet per second, and punching is not. Maybe I'm being overly simplistic in how I view this, but I just don't see the comparison.

However, I'm not a physics major by any stretch of the imagination, so perhaps its my simple brain not being able to comprehend the formulas here.

[Melau]

In physics any object that has a velocity is measured in meters per second, it being a bullet (in this example 930 meters a second) or it being a punch (in this case 8.23 meters a second).

[Wastelander]

I'm extremely bad at math and, therefore, physics. That said, I'm pretty sure the power of strikes is supposed to be measured by Impulse, not Force. Force is just part of the formula for Impulse.

http://hyperphysics.phy-astr.gsu.edu/hbase/impcal.html#c1

[sperki]

It is an interesting thought experiment. I need to look at you sources when I have more time (I have to get my boy to soccer practice), but assuming your measurements are correct, that's pretty awesome. Bullet has less mass but more velocity. 60 kg in a punch might be generous, that's likely more than half of a person's mass and would probably be quite unbalancing to put into a punch.

[OleOle]

As a new karateka I look forward to the day when I can punch with as much energy as a M16 bullet!!!

Alas, perhaps that day will never come?

[Harkon72]

You are right, it wont. A punch has an impact that is part alignment and form. Part energy and focus, but most of all, relaxation. The harder you consciously try and punch, the more energy you waste in the mechanics of the process. If you tense your body, the effort is contained in the structure of the machine. If you totally relax, and only form the shape of your punch on impact, the energy or force of the strike will be much greater. The statistic for a karate punch is that the greatest impact is made when the martial artist, sometimes when tired is working an effort of 80%. I don't know how they worked it out, but that is a figure that I have come across recently.

Keep punching and relax, you don't need a spring makiwara or a wooden dummy, I use a bean filled wall bag. You'll soon learn to focus and speed will come. If it hurts by the way, you're doing it wrong.

[Drew]

I'm extremely bad at math and, therefore, physics. That said, I'm pretty sure the power of strikes is supposed to be measured by Impulse, not Force. Force is just part of the formula for Impulse.

http://hyperphysics.phy-astr.gsu.edu/hbase/impcal.html#c1

+2

Impulse=mass x change in velocity. It's that change in velocity you need to be looking at. Obviously the difference in the starting and ending speed of a bullet is going to be a lot more dramatic than that of your fist, and even when multiplied by the relatively small mass of the bullet you are going to end up with a much higher impulse than any punch can provide.

I think you might be getting tripped up by thinking that force is always bad for you. Our planet is constantly pushing us about with an incredible amount of force, but doesn't crush us because there is (relatively) little change in velocity at any given point.

[DWx]

Somewhere I had a biomechanics paper that detailed the forces at work in a Karate a's punch... I'll see if I can dig it out.

I would agree though that it's not just the terminal speed and the mass at play but also how efficiently this is transferred and the change in velocity that occurs. It's very simplistic but think of it like this, if I'm in a car travelling at 60 mph and I see a stop light 30 feet away, I then slow the car down in a controlled manner over time to come to a complete standstill thus very little force is transferred. If I'm travelling along at 60 and all of a sudden there is an object in my path, I come to a very abrupt stop and that kinetic energy has to go somewhere, usually by completely crushing my bonnet and the object in front of me. Point is its not travelling at speed which results in a powerful collision, the rapid and sudden deceleration does:

http://sciencebasedlife.wordpress.com/2012/06/03/its-not-the-fall-that-kills-you/

That said, if you want to know the speed of your arm during a punch, it's pretty easy to measure. Film yourself punching then watch the video back and see how many frames it takes for your punch to travel to its target. If you know how many frames per second you were shooting at, you can then use this to work out the time it takes for you to punch. Divide the distance your arm travels by the number of seconds it takes to do it and you can work out the velocity of your punch.

[sensei8]

To me, all of the mathematics are akin to not seeing the forest because of all of the darn trees. Sure, study how to punch effectively across the board, but, don't be overwhelmed with the 'why' and 'because' of the punch, in that, the summation of 'why' is to the summation of 'because'!!

Once you understand how to effectively punch, and you're making solid penetrative contact to and through the target, you'll find something

else in your training that will cause you to ask...WHY?...and "BECAUSE!"...this is the beauty of Shu Ha Ri, isn't it?!!

It's important to study how things work and why they work and how to improve it...that's discovery. Take the darn thing apart and put it back together over and over until a more economic way to effectively apply a punch can replace the old method with the new method until that method is replaced...then so be it.

Sometimes the math of the whole darn thing gives me a splitting headache!! I can either baffle them with brilliance while on the floor or I can shower them with a truck full of dung or I can physically teach them how to execute a dynamically effective punch...I'll choose the last of the three.

"Oh, it's way over your head!" No, not the hands-on of it all, but, yes, the mathematics of it does leave me in the dust at times. Why? Because that's not how I was taught. No! I was taught on the floor in a hands-on methodology by someone who would say..."YES...That's it...do it again!!"...OR..."NO...that's not it...try it again".