Yes, spreading the impact over a larger surface area is important.
Most martial arts teach that a punch should be delivered with no more
than 2 knuckles. That's a tiny area for a lot of force. But to an
extent, force delivered to you head is force delivered to you head.
If you have to choose between being smacked over a 2 square inch
surface or a 4 square inch surface, choose the 4, but more important
than the surface area of the impact is the cushion effect of the glove
that the previous commenter mentions. This is important because of
the decceleration it provides prior to fist impacting face.
Newton's second law states that force=mass X acceleration. f=ma
This means that for a given mass (the fist, arm, and body weight
transferred forward by the boxer) the force delivered to your poor
jawbone is very dependent on the acceleration. (or
decceleration...decel is simply a negative value of acceleration. Not
negative in that it doesn't hurt...but negative in that we're actually
computing the force your face exerts to stop their hand, not the force
their hand exerts to move your face. But don't get excited, because
Newtons's 3rd law says that both numbers are the same. Doesn't matter
if his fist hits you or you hit his fist. His body's set up to handle
the energy at that time, and yours isn't. Have a nice nap.)
So as the glove makes contact, it starts bleeding off force. If the
glove doubles the time it takes for all the energy to transfer, then
it halfs the amount of force actually applied to your jawline. Now
the glove doesn't actually work in a linear fashion. When it first
makes contact it bleeds off very little force (provides very little
decceleration) but as the material compresses the ammount of force (or
rather ammount of decceleration provided) ramps up steeply, until it
can't compress anymore and the rest of the force is transferred as if
the glove didn't exist.) But the glove and your face interact for
MUCH longer than it would have taken for just the fist to interact
with you. (isn't interact a great word for putting you lights out?)
So it's a much more pleasant experience with the glove. Not all
gloves are equal. Boxing gloves are pretty generous to your face.
Sparring gloves are less so, counting on the fact that the vital
targets should be padded in those sports anyway. And the bag gloves
or wrestling gloves that UFC and MMA types spar in really provide no
noticeable protection to the person being hit- they're only there to
protect the knuckles of the person doing the hitting- kind of the
equivalent of a hand wrap, but much more manageable.
Now if anyone's still interested, here are some numbers. They're all
made up, but they'll illustrate the point. Let's pretend that a boxer
transfers 10 kilograms of weight into the punch. That's roughly
equivalent to 22 pounds. And let's say that this jab takes 1/10 of a
second to travel to full extension, and let's pretend that our boxer
has long arms- 1 meter.
So the AVERAGE velocity is 1 meter in 1/10 of a second, or 10 meters
per second. (10m/s) Now the punch starts at 0, in the middle travels
at this speed (10m/s) and thus at the end is travelling at 20m/s.
(once again- 10 is the AVERAGE value, between 0 and 20)
let's pretend the DECELLERATION (not the acceleration into the punch)
is 1/10 of a second. So the Decelleration expressed numerically is [
20m/s / .1 sec ] or
200 m/s per second
or 200 m/s^2
So if F=MA
then
force= 10 kilos * 200 m/s^2
so force=2000 Newtons (the unit of force.)
Now if the glove even doubles the time it takes for the impact to
occur ( and I suspect it more than doubles it) it halfs the
acceleration in that equation.
20m/s / .2 seconds. = 100 m/s^2
and force = 10 kilos * 100 m/s^2
so force = 1000 Kilos. Half the stimulation of pain nerves, and half
the rupturing of tiny blood vessels to cause bruising.
But you also have to remember that force will be applied for twice the
time... so the actual force applied to knocking you over is the same,
it's just done more gently.
Now another problem done with the same math, and it's everyone's 'make
the world a better place' education for today.
You're in a car travelling at 60 mph, which is aproximately 30 m/s.
You'r holding a 10 pound (aprox. 5 kilos) infant in your lap, and you
have an accident. The car comes to rest in .1 seconds. Can you hold
the child in your lap through the accident (assuming YOU are even
seatbelted in and not going flying through the windshield.)
Decel is 30m/s / .1 seconds, or 300 m/s^2
force = 5 kilos X 300 m/s^2
force = 1500 Newtons
which according to the unit calculator at
http://webphysics.ph.msstate.edu/units/index.html
is about 340 lbs And it only gets harder as Junior grows up.
How many of you can hold 340 lbs in your arms, working against the
weak side of your arm, and with little to no warning.
Hope this helped. |
