Learning More About Resonance
In his 1938 book, The Evolution of Physics, Einstein refers to two distinct
'substances' defined by classical physics that offers us a description of
reality: matter and energy. While we can easily point to what matter is, energy
is much more an elusive thing. From Richard Feynman's Lectures on Physics: “It
is important to realize that in physics today, we have no knowledge what energy
is …It is an abstract thing in that it does not tell us the mechanisms or the
reasons for the various formulas … [ but only that it is a conserved quantity ]”.
We do know how matter and energy can interact with one another in different
ways. With energy we can create forces that (for examples) moves matter
through space or changes its temperature. But there is one particular
interaction between matter and energy that turns out to be very interesting
and deserves special attention: resonance.
Scientists and Engineers define a 'System' as a collective of interacting parts.
Systems may be isolated (closed) or open (processing inputs and outputs).
Systems can be very simple, complex, natural or man made. A system can be as
small as an elementary particle within an atom or as large as a galaxy. Systems
exist within your body and power the electrical distribution of the International
Space Station. So in summary a system is generally anything we define it to be,
constrained by some physical boundaries and containing elements within that can
interact with one another and the world outside the system. While some
systems will simply and smoothly move from point A to point B when nudged by
an external force, others may have a tendency to ‘ring’ or oscillate along the
way. Ringing behavior is a clue that energy has been momentarily 'trapped'
within the confines of the system; and has entered the system at a rate faster
than it can be dissipated. The trapped energy can cause components within the
system to resound with vibrations characteristic of the particular system’s
internal structure. When the frequency of any external forces and that of the
internal structure of the system happen to match one another, and the energy
supply is unlimited, an amazing thing can occur. Energy gushes in and the system
is at great risk … of flying to pieces. That’s resonance in a nutshell.
copyright Mike Borrello Mar 2012
The Ruben’s Tube
The Ruben's tube offers a dramatic way of demonstrating standing acoustic
wave resonance in tubes. Here is Wiki on the Ruben’s tube
Examples on the Destructive Power of Resonance
See the historical Tacoma Narrows Bridge collapse to the music of Queen's
Bohemian Rhapsody. (No it wasn’t the music that led to the collapse!)
Helicopters may be stable in flight, but see what can happen when a running
helicopter is lashed to the ground. This video a good illustration of ground
A Seiche In Your Own Backyard!
A seiche is a standing resonant wave that can develop when the motion of a
surrounding container or tractional forces of wind match the natural
frequency of the body of water within. Historical accounts have recorded
destruction of entire lakeside villages during earthquakes. See what
happened to this swimming pool during the 2010 earthquake in Brawley, CA: