I am totally new to those vibration and frequency stuff.
I find the concept of resonance a bit confusing, it seems that there are various definitions of it
I know objects or mass vibrates at their natural frequency
bur in earthquake the seismic waves that it carries makes buildings vibrate mainly because those waves match or are close to the buildings natural frequency hence we say those buildings vibrate in resonant.. another exampe is the tuning forks, if you hit one tune fork the other one vibrates in resonant pickes up the signal??..
or is resonance the amplification in the amplititude, like the swing example.. a small force can produce larger and larger oscillation ?
I find the concept of resonance a bit confusing, it seems that there are various definitions of it
I know objects or mass vibrates at their natural frequency
bur in earthquake the seismic waves that it carries makes buildings vibrate mainly because those waves match or are close to the buildings natural frequency hence we say those buildings vibrate in resonant.. another exampe is the tuning forks, if you hit one tune fork the other one vibrates in resonant pickes up the signal??..
or is resonance the amplification in the amplititude, like the swing example.. a small force can produce larger and larger oscillation ?
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A resonant frequency is one that occurs when an incident frequency matches some whole number multiple of the natural frequency you already know about.
Those twin tuning forks, for example, have the same natural frequency, let's call it middle C for the sake of discussion. So when fork A is banged and set to vibrating at middle C, and all its harmonics (whole number multiples of middle C) those compression waves strike fork B nearby.
The first P wave hits fork B and gives fork B a bit of a nudge. Then there is rarification after some T/4 later where T is the period of the wave. But because the two forks have the same natural frequency, fork B is bouncing back in sync with that rarification of the incident wave. Then comes the next compression another T/4 seconds later, the same time fork B is oscillating away from the incident wave because its period T is the same period as the incident wave.
They are in sync. And that means constructive interference. Each quarter wave of the incident wave gooses the quarter wave of fork B. And that's like pushing the swing in sync with its period of oscillation. Each swing, each T/4 wave, the amplitude in fork B gets larger because the wave from fork A is pushing it in sync.
Things can get out of hand quickly when an object is resonant with some incident wave. Bridges have been known to be ripped apart when the wind gusts were in sync with the bridge. And that caused the bridge to oscillate with increasing amplitude until it could no longer stand the stress and literally fell apart. And I think we've all heard tales about opera singers who could break fine glass by singing a tone in sync with the glass' resonant frequency.
Those twin tuning forks, for example, have the same natural frequency, let's call it middle C for the sake of discussion. So when fork A is banged and set to vibrating at middle C, and all its harmonics (whole number multiples of middle C) those compression waves strike fork B nearby.
The first P wave hits fork B and gives fork B a bit of a nudge. Then there is rarification after some T/4 later where T is the period of the wave. But because the two forks have the same natural frequency, fork B is bouncing back in sync with that rarification of the incident wave. Then comes the next compression another T/4 seconds later, the same time fork B is oscillating away from the incident wave because its period T is the same period as the incident wave.
They are in sync. And that means constructive interference. Each quarter wave of the incident wave gooses the quarter wave of fork B. And that's like pushing the swing in sync with its period of oscillation. Each swing, each T/4 wave, the amplitude in fork B gets larger because the wave from fork A is pushing it in sync.
Things can get out of hand quickly when an object is resonant with some incident wave. Bridges have been known to be ripped apart when the wind gusts were in sync with the bridge. And that caused the bridge to oscillate with increasing amplitude until it could no longer stand the stress and literally fell apart. And I think we've all heard tales about opera singers who could break fine glass by singing a tone in sync with the glass' resonant frequency.