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Vibration is the mechanical
oscillations of an object about an equilibrium point. The oscillations may be
regular such as the motion of a pendulum or random such as the movement of a
tire on a gravel road.
Frequency
A vibrating object moves back and forth
from its normal stationary position. A complete cycle of vibration occurs when
the object moves from one extreme position to the other extreme, and back
again. The number of cycles that a vibrating object completes in one second is
called frequency. The unit of frequency is hertz (Hz). One hertz equals one
cycle per second.
Amplitude
A vibrating object moves to a certain
maximum distance on either side of its stationary position. Amplitude is the
distance from the stationary position to the extreme position on either side
and is measured in metres (m). The intensity of vibration depends on amplitude.
Acceleration (Measure of Vibration Intensity)
The speed of a vibrating object varies
from zero to a maximum during each cycle of vibration. It moves fastest as it
passes through its natural stationary position to an extreme position. The
vibrating object slows down as it approaches the extreme, where it stops and
then moves in the opposite direction through the stationary position toward the
other extreme. Speed of vibration is expressed in units of metres per second
(m/s).
Acceleration is a measure of how
quickly speed changes with time. The measure of acceleration is expressed in
units of (metres per second) per second or metres per second squared (m/s2).
The magnitude of acceleration changes from zero to a maximum during each cycle
of vibration. It increases as vibrating object moves further from its normal
stationary position.
What is resonance?
Every object tends to vibrate at one
particular frequency called the natural frequency. The measure of natural
frequency depends on the composition of the object, its size, structure, weight
and shape. If we apply a vibrating force on the object with its frequency equal
to the natural frequency, it is a resonance condition. A vibrating machine
transfers the maximum amount of energy to an object when the machine vibrates
at the object's resonant frequency.
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