Grandmaster Ken MacKenzie - Taekwondo Times

By Erik Richardson
Over the course of centuries, the greatest
martial artists have been working to solve a very
complex set of physics problems, even though
they rarely thought of it in terms of physics,
about using the mass of the human body to create
the maximum amount of force. In trying to
understand a lot of areas of life, a little science
goes a long way. It is similarly true that a little
math can go a long way in understanding science.
We will look at a key equation from physics
involving mass and energy, and we will see how it
relates to the ongoing experiment to improve our
training and our success in martial arts.
Mass, Speed & Energy
At the heart of the physics of martial arts is
a simple equation for calculating kinetic energy.
We can think of any of the strikes and blocks
in martial arts in terms of energy. Energy just
means how much work something can do—
meaning the size of an object it could move and
how far it could move it. The “kinetic” part of
kinetic energy comes from the Greek word for
motion. Kinetic energy is the amount of work
something can do because it is in motion. The
equation for the kinetic energy of an object
is:
KE = ½ m.v 2
In this equation, m stands for the
mass of an object, and v stands for its
speed.
There are a couple of important things to
notice right away. The first is that the kinetic
energy of an object depends on both its mass and
its velocity (speed). In physics, the velocity means
both the speed and direction of an object. But
since we are looking simply at forward movement
in these cases, it works better to use speed and
velocity interchangeably.
The second thing to notice is that the velocity
counts for significantly more than the mass. To
appreciate the impact of the difference, let’s look
at three different scenarios. The first is throwing
a baseball at 40 miles per hour (mph); the second
would be increasing the size by 40 percent , such
as throwing a softball at 40 mph; and the third
scenario would be increasing the speed by 40
percent, like throwing a baseball at 56 mph.
1. Baseball @ 40 mph:
½ . (.1417kg) . (17.8 meters/second) 2 = 22.44
Joules ( J)
2. Softball @ 40 mph:
½ . (.2kg) . (17.8 m/s) 2 = 31.93 J
3. Baseball @ 56 mph:
½ . (.1417kg) . (25.03 m/s) 2 =
44.39 J
Joules is a measurement
of energy. By comparing
these numbers we
can see that increasing
the mass by 40 percent
64 November 2009 / taekwondotimes.com