MadSci Network: Physics |
Thank you for your question Salman Akbar
I hope you will be able to understand that what you have asked is a very
fundamental question about matter and energy and as a result the answer I give
will be subject to some theoretical understanding of matter. Theories are not
proved. In this case we have pretty good data to suspect that the theories
are right but they are still just good guesses. My answer will also be
somewhat incomplete because of this.
Also I hope you will feel free to look more deeply into this matter in the
future as the issue of how matter transmits energy is one very fundamental
question which will contain many answers to things we want to do in the future.
The answer in very short has to do with energy. All energy transfers are
electromagnetic, so strangely enough mechanical waves are electromagnetic
waves in terms of energy. We all know that they look much different.
I must say that nobody has yet come up with a true explanation of what
electromagnetic waves are. We have a lot of guesses.
Matter is connected together by electromagnetic bonds. Exactly how these work
is not well understood but we have some working models. Basic Atomic theory
indicates that electromagnetic forces bond matter together and these bonds are
elastic. They can stretch or bend.
Imagine if you will a set of 2 heavy steel balls connected by a coiled spring.
If you pull the balls far apart the spring will pull the balls back together
until they bounce off each other if you let them go. The spring in this case
is like the bonding force between two or more atoms. The weight of the
balls in relationship to each other will determine the rate at which they
move and which ball will move more than the other.
As some springs are stronger than others and some are quicker in action than
others so bonds don t all act in the same way. There are bonds between matter
that are strong like the chemical bonds and others which are weak like the
bonds that hold together the powder that makes up a pill when it is pressed
in a pill press. Other bonds are even weaker. In the case of mechanical
waves the bonds that hold the material together vary. It depends on the type
of the material in question.
A laser is a special kind of light which is tuned so that the bonds of the
chemicals that glow and form the beam of light can be stretched all together
and in a specific way. (Bend or stretch on a specific bond) We can measure the
stretch by the wave length of the light from the laser. This powerful
stretching adds up to a very bright and powerful light when released.
The mirrors that encase a laser merely cause the light to bounce back and
forth many times building up force in the light wave by pushing the matter
back and forth. The wave length determines the color of the light and tells
us the length of the stretch in the bond and which bond stretched.
A lithotripsy machine used to break up kidney stones inside of a living person
uses the fact that this laser light can bounce matter very hard. These hard
bounces cause the shock waves in matter that converge on the stone and shatter
it.
You may have seen a similar thing in a sloshing water tank or in a bathtub
where you slosh back and forth adding one wave on top of the other until the
wave gets very high. The ends of the tub act just like the mirror in a laser. Mechanical waves such as in water tend to be the product of very long distance bonds that bond the water loosely together. Thus when a shock or push is added it takes some time for the energy to transmit and the matter around gets squished up and together. Thus the bond force gets transmitted very slowly. There are more types of bonding than just chemical bonding.
Mechanical waves of this type which involve the compression or motion of
matter vary in speed and method of movement depending on the media involved.
A steel ball transmits a wave very fast because it is solid and very strongly
bonded. Water transmits the wave slower and you see the wave more easily
because the water piles up in a wave you can see. If you had a very fast
camera you could see the steel has a similar wave but is must smaller because
of the type of wave solids tend to transmit more easily.
Gasses also transmit waves. The speed of a wave traveling in a gas in known
as the speed of sound. Since the air has different densities, it has
different speeds of sound. This relates to the nature of the bonding of the
air together and the mass being moved.
Electromagnetic waves transmit directly to a bit of matter over a distance or
may cascade from matter to matter. This is in the form of either light,
electrical currents, or magnetism. (J. K. Maxwell wrote that light
electricity and magnetism were clearly manifestations of the same force, in
1864 and to date it appears he is correct) In any case these waves eventually
move matter somewhere. Since it is energy that bonds matter together any
movement of matter involves these waves. Even the gravity accelerations we
see in matter have electromagnetic effects.
So generally we assume that mechanical motions are not related to
electromagnetism since they appear unrelated to electromagnetism.
They still involve the transmission of electromagnetic energy. Exactly
what electromagnetism is has not yet been determined. It is more understood
as existing than what it is. This is a matter for substantial study in
Sub Atomic Physics. We really do not know how matter is linked together
but we know it is.
Some Mechanical Wave forms which are determined by which way the matter is
moved are Lateral waves: These travel in a line through the medium and
generally are expressed as a direct in line push of matter.
Transverse waves: These travel in a line by way of displacing matter
perpendicular to the wave motion and in water represent a rolling of
atoms in the wave.
Ocean Waves are primarily lateral in deep water and become transverse in
shallow water. This is why waves appear taller at the shore than out to sea.
They are composite having the behavior of both types of waves.
In an earthquake the rocks transmit lateral waves until they meet wet ground
or water. The water converts the wave into a transverse wave. The result is
that buildings on a bedrock foundation generally are not bothered by
earthquake but those on wet soils are bothered.
Some Electromagnetic Wave Forms:
A beam of light is an electromagnetic wave. So is an AC current.
A magnet clearly emits electromagnetic waves as that is where we get the term.
In the end all of these waves are nothing but one of the many ways energy
transmits through the our world. It is a question of what is being bumped and
what it is hooked to by way of an electromagnetic bond.
I hope this answer lets you see:
[1] that there is a lot we need to learn and
[2] that everything is attached in some way and
[3] we are only now starting to understand.
Waves do many things in our world that we don t even think about. In your
area they shape the sand on the Saudi Arabian Desert. They form the clouds
and determine the wind in how it acts. They even heat and cool us. All of
the motion of matter around us is determined by these waves. The fact that
the distance at which the wave varies or the speed at which it is moving
varies determines what kind of wave we see. I don t know any place you can go
to learn about exactly how each wave form transmits its energy to another.
Much of the science of remote detection relies on the more basic understanding
of how energy interacts and makes up matter.
Here are a few simple experiments you may be able to do to see what I have said.
Try the links in the MadSci Library for more information on Physics.