Article
Where
Does the Power Come From?
By
Andrew George
Andrew
George started Karate at the Mildura Dojo in 1983 under Sensei Pat Zappia.
Early training was mostly in Sempai Corey Parker's classes until moving to
Melbourne in 1985 to attend university.
After moving to Melbourne, training was with Sensei Omer Cukovic and Andrew
soon found it difficult to balance Karate training with study. Coming from
the country and getting used to life in the big city whilst working a part
time job didn't leave much spare time. So Karate was the inevitable casualty.
It wasn't until after establishing a career, getting married and starting
a family, and working on a long list of other projects - that the time was
right to get back into regular Karate training. A visit to Sensei Takahashi's
seminar and grading at MSAC in 2004 provided the motivation, and Andrew resumed
training with his son Alexander soon after.
Karate is again Andrew's main interest, a JKA Shodan, he now trains at the
MSAC Dojo under Sensei Lloyd Baggott, whilst also attending other Melbourne
Dojos when time permits. Andrew works as a managing engineer at an automotive
manufacturer and supplements Karate with weight training - again when time
permits. One of Andrew's interests within Karate is study of the science behind
the techniques, and is actively using the combination of weight training and
Karate to develop knowledge in that area. This article is the first from that
study.
The
topic was raised in reference to Newton’s laws and their applications
in Karate. |
This
is the result of a discussion with Sensei Lloyd Baggott after training one
night. The topic was raised in reference to Newton’s laws and their
le describing
my thoughts.
The first step is to explore the parameters involved. You don’t need
a detailed knowledge of these to understand the basis of the article, but
this background information will help you to put the big picture together.
The basic parameters are mass, velocity, acceleration, and force.
Mass -
is a measure of how much matter a body contains, which is the effect of the
total number of electrons, protons and neutrons. The unit for mass
is the Kilogram (k ss is the same on Earth as it would be on the Moon. This is because the
number of particles in your body will be the same (read on, there’s
more to this later).
Velocity –
is the rate that a body changes its position (in a certain direction) in time.
Think of velocity as speed, but where direction is also important. So if you
are traveling toward a target in an arc, your speed will be higher than your
velocity in the direction of your target, because only the decrease in straight
line distance towards your target is contributing to your velocity toward
the target.
Velocity (v) = distance (s) / time (t)
The normal unit for velocity is meters per second, but we can also
convert to kilometers per hour.
Acceleration
– is the rate of increase or decrease in velocity.
So if the velocity of a body changes, there is acceleration associated with
the change.
Acceleration (a) = velocity (v) / time (t)
Force
– Force is a push.
Weight is a force. Because we don’t normally measure mass directly,
we measure the force that mass exerts under gravity. That’s where the
bathroom scale comes in, as it is designed to measure force and then convert
this to a mass in kg. The unit of force is the Newton.
Confused with mass and weight? Weight is dependent on your mass and gravity.
So back to the moon example - as your mass on the moon is the same as it is
on Earth, your weight (or force exerted on the ground) will change as you
travel away from the Earth. This is because the effect of gravity reduces
as you travel away. And because the gravitational pull of the Moon is lower
than the Earth, your weight will be lower on the moon – even though
your mass didn’t change.
Now
you have the parameters needed for a study of Newton’s Laws in
Karate. |
Bathroom
scales are calibrated to the Earth’s gravitational pull, so you would
need different bathroom scales if your bathroom was on the moon. Now you have
the parameters needed for a study of Newton’s Laws in Karate. So what
are the laws?
I don’t think Newton practiced Karate. But his concepts are applicable
to Karate, just as they are in sending a Space Shuttle into orbit or working
out why an apple falls from the tree overhead. Newton developed and proved
three basic laws. They are:
1. Unless a resultant or unbalanced force acts on a body,
its velocity will not change. In my words – this means that movement
or change in velocity will not occur without application of a force or push.
2. The acceleration of a body is proportional to the
resultant force that acts on it, and inversely proportional to its mass. In
my words - the relationship here is force (f) = mass (m) x acceleration (a).
So the force required to accelerate a higher mass is high and the force required
to accelerate a smaller mass is low. The mass here could be your whole body,
or your fist or foot being thrust towards your target.
3. If a body A exerts a force on body B, body B exerts
a force on body A, equal but opposite in direction. In my words –
if you strike, push, or accelerate another body, the force you apply to that
body will also be applied back equal and opposite.
The choku zuki (straight punch in shizen tai - standing position) technique
can be used to illustrate an application of these laws.
This
downward force creates a clamp between the Karateka’s feet and
the floor. |
We
should start this study by considering the “system” to be used
in the example. Imagine a Karateka standing on the floor. He or she has a
weight force acting in a downward direction that is dependent on the Karateka’s
body mass. This downward force creates a clamp between the Karateka’s
feet and the floor. This clamp has the potential to resist movement of the
feet on the floor by the friction force created by the weight of the Karateka’s
body mass. The type of floor surface and foot size also has an effect on friction.
Another aspect of the system is the moving parts of your arms that make up
the striking technique. Let’s assume that the technique begins with
the left arm outstretched and the strike will be performed with the right
fist. The movement is initiated by combined movement of the left arm toward
the hip at the same time the right arm is thrust toward the target.
It
is common in dynamic Karateka to see a full body windup to a powerful
punch. |
It
is common in dynamic Karateka to see a full body windup to a powerful punch.
This involves a vibration or twisting of the upper legs and torso which is
used to increase acceleration of the punching and returning arms. The torso
movement allows a greater force to accelerate the fist at a greater rate.
We can now analyse the system comprising the movement of the body, and the
reaction at the floor using Newton’s laws. The choku zuki technique
creates a body movement, and we know from Newton’s 1st law that a body
cannot move without a force being applied.
Newton’s 2nd law dictates that a Karateka with more moving mass or who
executes a faster technique (i.e. more acceleration of body and limbs) will
need to apply a higher force to accelerate his or her limbs. But where does
this force come from?
This is where Newton’s 3rd law comes in. The force actually comes from
the floor, or more accurately – the Karateka’s link with the floor
due to the friction caused by the Karateka’s weight, the size of his
or her feet, and the type of floor surface.
Newton’s 3rd law describes the friction caused between the feet and
the floor as an equal and opposite force to the forces needed to execute the
Karate technique.
This also means that the forces created by the windup and execution of the
punch cannot exceed the force that the Karateka can “hold” onto
the ground with. So although technique and skill is a major factor –
the link with the ground can theoretically limit the effort that can be put
into the technique.
You can experiment with this by jumping off the ground and even trying this
technique on a trampoline. But the acceleration you are able to apply into
the technique will be limited, as you will not have the grip on the floor
to drive your technique.
Newton’s
laws can even be used in Karate! |
So
we can answer the question of where does the power come from, as the power
associated with the movement of limbs comes from the Karateka’s connection
with the floor. And the higher the mass of the moving limbs or the higher
the acceleration of the mass – the higher the reaction force at the
connection with the floor is required. Newton’s laws can even be used
in Karate!
Note:
I have referred to power in the article in the popular sense of the word that
means “a mechanical advantage or effect”, where the scientific
numerical parameter for power is actually the quantity of work that can be
done in a certain time.
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