THE VIBRATIONS or oscillations of mechanical systems constitute
one of the most important fields of study in all physics. Virtually
every system possesses the capability for vibration, and most
systems can vibrate freely in a large variety of ways. Broadly
speaking, the predominant natural vibrations of small objects
are likely to be rapid, and those of large objects are likely to be
slow. A mosquito's wings, for example, vibrate hundreds of
times per second and produce an audible note. The whole earth,
after being jolted by an earthquake, may continue to vibrate at
the rate of about one oscillation per hour. The human body itself
is a treasure-house of vibratory phenomena; as one writer has
put it 1 :
After all, our hearts beat, our lungs oscillate, we shiver when
we are cold, we sometimes snore, we can hear and speak because
our eardrums and larynges vibrate. The light waves which permit
us to see entail vibration. We move by oscillating our legs. We
cannot even say "vibration" properly without the tip of the
tongue oscillating. .. Even the atoms of which we are consti-
tuted vibrate.
The feature that all such phenomena have in common is
periodicity. There is a pattern of movement or displacement that
repeats itself over and over again. This pattern may be simple
IFrom R. E. D. Bishop, Vibration, Cambridge University Press, New York,
1965. A most lively and fascinating general account of vibrations with par-
ticular reference to engineering problems.
one of the most important fields of study in all physics. Virtually
every system possesses the capability for vibration, and most
systems can vibrate freely in a large variety of ways. Broadly
speaking, the predominant natural vibrations of small objects
are likely to be rapid, and those of large objects are likely to be
slow. A mosquito's wings, for example, vibrate hundreds of
times per second and produce an audible note. The whole earth,
after being jolted by an earthquake, may continue to vibrate at
the rate of about one oscillation per hour. The human body itself
is a treasure-house of vibratory phenomena; as one writer has
put it 1 :
After all, our hearts beat, our lungs oscillate, we shiver when
we are cold, we sometimes snore, we can hear and speak because
our eardrums and larynges vibrate. The light waves which permit
us to see entail vibration. We move by oscillating our legs. We
cannot even say "vibration" properly without the tip of the
tongue oscillating. .. Even the atoms of which we are consti-
tuted vibrate.
The feature that all such phenomena have in common is
periodicity. There is a pattern of movement or displacement that
repeats itself over and over again. This pattern may be simple
IFrom R. E. D. Bishop, Vibration, Cambridge University Press, New York,
1965. A most lively and fascinating general account of vibrations with par-
ticular reference to engineering problems.
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