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rifling was first used as a place for the soot from the black powder to go when building up in the barrel, before rifling too much soot could cause a jam. the turning of the rifling probaly came from archers noticing that arrows that spun were more accurate. and the upwards angle of the bullet when it leaves the barrel probaly has to do with recoil of the gun also
bullets that aren't round will tumble after they come out of the barrel without and gyroscopic stabilization
akira: kevlar will also stop bullets up to a certain caliber, you need the plates for protection from bigger bullets, that is why the plates are over the vital areas like heart and lungs, kevlar is used for comfort and flexiblity instead of having old school plate mail armor
Bud shi dist: the spin of the bullet has nothing to do with it's ability to "defy gravity" for the bullet to seems as it is not falling it needs to have a velocity high enough that the fall of the bullet maches the drop off of the horizon of the earth, you basically would want a bullet to orbit the planet to make it seem to defy gravityLast edited by EnaeS; 10/21/2005 3:00pm at .

Style: Judo newbI've seen quite a few posts get close to my understanding of the basic physics in a strike, but then shy off again. With this in mind, I will try to simplify what I know in a nice series of incomprehensible symbols and liberal use of the words "Qi," "innerself," and "****tards." As a side note, I was able to complete both necessary physics courses for my aspired mech. eng. degree (physics 1 & 2 as they were called at NAU) before deciding I hated engines and machines and leaving college.
So far we have these identities to work with (these are taken from http://physics.about.com/od/glossary unless otherwise noted):
T = time = there are some incredibly FUN attempts to define time. I like Einstein's best when he said, "Time is what my wristwatch measures."
D = distance = having a hard time finding the actual definition, but should be pretty straightforward. The only thing to not is that distance and displacement are different. If you walk 5 feet, then return to where you started the distance travelled is ten feet, but the displacement is zero. Displacement is distance from a starting point at any given time.
M = mass = Mass is the quantity of inertia possessed by an object or the proportion between force and acceleration referred to in Newton's Second Lar of Motion (which this is). (mass and inertia are not dependant on anything other than how much matter is in an object, the best equation to find it is M = F/A)
S = speed = The rate or a measure of the rate of motion, especially distance traveled divided by the time of travel. (S = D/T) (from http://www.answers.com/topic/speed)
V = velocity = A vector quantity whose magnitude is a body's speed and whose direction is the body's direction of motion. (V = (D2  D1)/T) (from http://www.answers.com/topic/velocity) Note the difference in S and V  this means while speed can only be positive or zero since it has no relation to direction, velocity can be negative (i.e.  you're going backwards)
A = acceleration = a vector quantity which is defined as "the rate at which an object changes its velocity." An object is accelerating if it is changing its velocity. (A = (V2  V1)/T) (received from http://www.glenbrook.k12.il.us/gbssc...Kin/U1L1e.html) Again, acceleration can be positive or negative (speeding up or slowing down). I think much of the confusion here relates to this term.
Mo = momemtum = Momentum is the product of an object's mass and velocity. It is a vector. (Mo = MV)
F = force = Force is a quantitative description of the interaction between two physical bodies, such as an object and its environment. Force is proportional to acceleration. In calculus terms, force is the derivative of momemtum with respect to time.
Contact force is defined as the force exerted when two physical objects come in direct contact with each other. Other forces, such as gravitation and electromagnetic forces, can exert themselves even across the empty vacuum of space.
Force is a vector (dependant on direction). The SI unit for force is the newton (N). One newton is equal to 1 kg * m/s2.
K = Kinetic Energy = energy associated with moving objects (K = .5M(V^2)) (from http://library.thinkquest.org/20331/...s/keandpe.html)
P = power = Power is the time rate at which work is done or energy is transferred. In calculus terms, power is the derivative of work with respect to time. (Po = W/t)
W = work = Work is defined (in calculus terms) as the integral of the force over a distance of displacement. (W = FD)
Yes, I am taking a baby steps approach and I have no doubt most to all people here know this already, but not defining terms gets a person in trouble and causes lots of muck as we have seen already.
So now that we have our terms and relavant equations, let's see which ones apply, and how.
The main thing being wondered is what produces the most "oomph" in a strike. I use the word "oomph" (perhaps pain would be better) to avoid confusing terms such as energy, force, and power.
The first thing I will say is that the equation F=MA does NOT help in this query. Why? Because as stated before, this is to determine how much force is required to get our fist/arm/body/etc. moving to strike the ****tard (told you that would be in here). For example, let's say you're some idiot and are simply punching from your shoulder (for simplicity's sake) and your fist is currently stationary in guard. Then there is a mass of 5 kg (arbitrary  you've got a pansy hand), but speed is zero, thus acceleration is zero, thus force is zero at this moment. When you punch, let's assume your fist reaches a max speed of 10 m/s in about .1 sec. This means the force required for you to do this was:
F = 5((V2  V1)/T)
= 5((10  0)/.1)
= 5(10/.1)
= 5(100) = 500 kg*m/s^2, or 500 N
Now here's why this equation doesn't help us. While it is true that in a perfectly elastic collision, this force would transfer to the face of the ****tard, increasing the mass would only increase the amount of force required to attain the same acceleration. So what about increasing the accleration? The only thing that does is makes it so you can reach the same speed in less time.
So what equation is better to look at? Kinetic Energy: K = .5M(V^2)
It is here in this equation that we can see why a bigger person hits harder, but that a faster blow hits even harder. (Of course, a bigger man with a fast blow hits hardest...except for those with Qi. There, got that in too.) This is also why so many people like to stress speed over strength  unfortunately to the detriment of strength training, which is stupid. Let's go back to the example of the pansy hitting the ****tard to prove his innerself isn't gay. This time we'll put the data in the K equation.
K = 5(10^2)
= 5(100) = 500
(Note, while the number is the same with force and energy here, the SI are not. F = kg*m/s^2 while E = kg*m^2/s^2  so while I don't think I messed up the SI, this is just a happy coincidence. If the time it took to accelerate was .2 s, then F = 250N, while K would still be 500J.)
Same answer, what does it mean? Nothing yet, but let's try playing around with the numbers. Let's say you realize your pansy hand needs more muscle, so you bulk up to a nice 10 kg hand, but you still punch at the same speed.
K = 10(10^2)
= 10(100) = 1000
You've doubled your Energy. But let's go this route. Instead of bulking up your hand, you go take some fencing or whatever and build up your speed instead, and now you've doubled how fast you're fist is going when it hits the target.
K = 5(20^2)
= 5(400) = 2000
Instead of doubling the energy, you've quadrupled it. Speed increases the energy of a strike much more than the mass behind it.
Now, obviously this doesn't mean abandon strength training. Speed comes from muscles, and I believe it was already pointed out that a balance needs to be there. A little like rocket science problems  more lift means more fuel needed which means more weight which means more lift needed. A delicate balance is required. What this does mean is that working your fasttwitch muscles will add more energy to your strike than working your slowtwitch (or whatever they're called).
Also, while I am tryiong to show that F=ma is the wrong equation to use, the aspect of acceleration cannot be ignored. Acceleration gets your fist from zero to blindingly fast in the shortest amount of time possible. Less time means less chance of them seeing it and responding. It also helps in close quarters, where there's less distance for your strike to travel.
As for why it is more powerful to "hit past" your target, I am not certain as to the physics of it, but I would propose it to deal with 1) deformation of the target which depends on 2) transfer of energy. This ties in with power, or the transfer of energy over time. This is why the whole tighten just on impact then relax is there  it transfers the energy faster, thus more power.
There  I hope this will help the waters more than stir up more ****tard Qi practicioners who are worried about their innerselves. 


OOOOOOOOOOAAARRGGHH RLY?
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 Nov 2004
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 Americastan
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Posted On:
5/24/2006 7:24pm 
Prophet of Apathy
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 Jan 2006
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Posted On:
7/24/2006 5:12pm
Style: MMAThere's plenty of interesting information here, but using theoretical physics terms can muddy the waters somewhat.
For instance, "Power" in the context of exercise physiology means the ability to contract a muscle at about 30% of it's MVC (maximum voluntary contraction) at the greatest possible speed. Martial arts of all kinds are very much power sports.
For example, a martial artist, let's call him Tank, can bench 600lbs. If he wanted to train power he would lift 180lbs as fast as he possibly could (and still control it obviously). This transfers to punches, throws and takedowns, for instance, which are all done at high speed.
Think of a spectrum somewhere between the lumbering lumberjack overhand and the much maligned Wing Chun lightning slap. A power punch exists somewhere between these two. The ability to lift a heavy weight in a slow controlled manner doesn't recruit the same kind of muscle fibers in the same proportion, nor does the ability to throw a superfast strike with no mass behind it.
Now it's true that, in a sense, a punch is a power activity only for the last part, the contact and postcontact or throughcontact period. This is where you encounter the resistance. But this is where training neuromuscular recruitment comes in (the heavy bag for instance) so that you recruit the right muscle groups and fibers at the right time. 
Heavyweight
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 Oct 2003
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Posted On:
1/10/2007 10:47amIn the course of my work I ran across a paper for NASA on the modeling of human body under various loading conditions. If people are interested in a more than layman's approach, it might be a good read.
The objective is to construct a framework wherein the various models of human biomaterials fit in order to describe the biodynamic response of the human body. The behavior of the human body in various situations, from low frequency, low amplitude vibrations to impact loadings in automobile and aircraft crashes, is very complicated with respect to all aspects of the problem materials, geometry and dynamics. The materials problem is the primary concern, but the materials problem is intimately connected with geometry and dynamics.
http://ntrs.nasa.gov/search.jsp?R=71...vestDate%257c1 
Registered Member
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 Oct 2007
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Posted On:
3/01/2008 5:45pm
Style: undecidedsweet thread and Maverickz really knows what he is talking about, sounds like one of my profs my theory is that the best punch results in the maximum amount of force being transfered into the object you are hitting, i believe to do this and throw an effective punch you have to minimize the amount of force being put back into you upon connection with the target as well as ensure that most of the energy being directed into the object you are hitting is not disbursed through the object but concentrated and absorbed(in a way of speaking) in a smaller area. ( i believe this causes the most damage). I believe that strength training helps with the first thing i said( about the energy transfer back into you) and i believe technique helps with both things i mentioned. (punching through the target, predicting actions, and knowing where to hit and how to hit; and thus cause the most damage)
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Posted On:
8/07/2005 8:45am
Style: hung gar  self taught