In: Civil Engineering
What is resonance? Is it possible to experience a perfect resonance or it is just a theoretical term?
Resonance occurs when a material oscillates at a high amplitude at a specific frequency. We call this frequency resonant frequency. The dictionary defines resonance as,
“the state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus is the same, or nearly the same, as the natural vibration frequency of the system.”
Physics defines Resonance as
A phenomenon in which an external force or a vibrating system forces another system around it to vibrate with greater amplitude at a specified frequency of operation.
Below we have listed examples of resonance that we can witness in our daily lives:
The best examples of resonance can be observed in various musical instruments around us. Whenever any person hits, strikes, strums, drums or tweaks any musical instrument, the instrument is set into oscillation or vibration at the natural frequency of vibration of the instrument. A unique standing wave pattern defines each frequency of vibration as a specific instrument. These natural frequencies of a musical instrument are known widely as the harmonics of the specified instrument. If a second interconnected object or instrument vibrates or oscillates at that specified frequency then the first object can be forced to vibrate at a frequency higher than its natural harmonic frequency. This phenomenon is known as resonance i.e. one object vibrating or oscillating at the natural frequency of another object forces the other object to vibrate at a frequency higher than its natural frequency.
One of the familiar examples of resonance is the swing. It is common knowledge that the swing moves forward and backwards when pushed. If a series of regular pushes are given to the swing, its motion can be built. The person pushing the swing has to sync with the timing of the swing. This results in the motion of the swing to have increased amplitude so as to reach higher. Once when the swing reaches its natural frequency of oscillation, a gentle push to the swing helps to maintain its amplitude due to resonance. But, if the push given is irregular, the swing will hardly vibrate, and this out-of-sync motion will never lead to resonance, and the swing will not go higher.
Group of soldiers marching on the bridge are asked to break their steps very often because their rhythmic marching can set extreme vibrations at the bridge’s natural frequency. The bridge can break apart if the synchronized footsteps resonate with the natural frequency of the bridge. One of the examples of the above is the Tacoma Bridge Collapse, where the frequency of the air matched with the frequency of the bridge leading to its destruction.