Chapter 52 (1/2)
Resonance is a physics phenomenon where amplitude increases when the frequency of a periodically applied force is equal to the natural frequency of the system on which it acts. These frequencies are known as the resonant frequencies. At these frequencies, a small amplitude of a periodic force could result in large resultant amplitudes.
The phenomenon of breaking glass with sound waves that we see on television is not because of the volume of the sound. Rather, it is because the frequency of the sound waves are the same as the glass’ natural frequency. The energy as a result of resonance is able to break the glass.
In the early 19th century, a troop of Napoleon’s soldiers marched in unison across a bridge under the command of their commander. However, when they were halfway through the bridge, the bridge suddenly vibrated strongly and collapsed, causing many soldiers and citizens to fall into the river and die.
After investigation, resonance was the reason for the accident! When the troop marched together, the frequency generated was the same as the natural frequency of the bridge. This caused the amplitude of the bridge to increase. When its amplitude was greater than the limit that the bridge could take, the bridge collapsed.
Similarly, if the 24 girls danced at the same frequency as the natural frequency of the glass bridge and caused resonance…
Crack!
Without any doubt, the glass bridge would collapse.
One would definitely die if one fell from an altitude of 723 meters!
It looked as though nothing was happening now as the frequency of the girls had yet to match the natural frequency of the glass bridge. However, when their frequencies matched, it would be too late.
For his own safety and others’ safety, Cheng Nuo thought that he should remind the girls.
“Stay here and don’t move, I will be back soon.” After instructing the others, Cheng Nuo walked onto the glass bridge by himself.
Cheng Nuo walked quickly to the young girl who was leading the group. The loud music made him frown.
“Eh, please give way, we are recording a video here!” said Zhao Meng to Cheng Nuo.
Zhao Meng was the organizer of the mass dance. Dancing on the streets could no longer satisfy their desire. Therefore, they formed a group and came to the famous glass bridge of Qing Cheng to film an interesting video. After that, they could upload the video onto the internet and get the public to watch it.
When a youth blocked her and disrupted the video recording, she was definitely annoyed.
“Pretty girl, can you ask your friends to stop?” said Cheng Nuo nicely. “What you are doing is dangerous. The glass may break easily.”
“Break?” Zhao Meng smiled and said, “Handsome lad, do you really think the glass bridge is like the glass windows in your house?
“Don’t worry, even if you jump on this glass bridge, it won’t break!”
As she said that, she jumped on the glass bridge and said, “Look, nothing happened.”
Cheng Nuo was angry.
Clearly, Zhao Meng thought he was a country bumpkin who was seeing the glass bridge for the first time.
Cheng Nuo continued to explain himself, “Pretty lady, I am not referring to this. Resonance! Have you heard of resonance?”
“Resonance? What is that?” Zhao Meng was stunned.
Cheng Nuo looked at the girls who were still jumping and dancing on the bridge in fear and briefly mentioned the danger of resonance.
Zhao Meng looked at Cheng Nuo with a gaze of “don’t try to lie to me because I am not as educated as you”. She said, “Are you… lying?”
Zhao Meng never heard of things like “natural frequency” and “resonant frequency” and did not really believe what Cheng Nuo had just said. However, he had no reason to lie to her.
Sigh!
Cheng Nuo did not give up. He took out his phone and keyed in a search for resonance. Then he clicked on a video and showed Zhao Meng.
Zhao Meng looked over.
The video was only ten seconds.
Initially, eight to nine girls were dancing on the glass bridge. However, the glass bridge in the video was in between two buildings instead of in the mountains.