The car crossed the bridge. Why does the bridge shake?

Because vehicles crossing the bridge will produce resonance.

Because vehicles will resonate when passing through the bridge, which will lead to the collapse of the bridge beam in serious cases, flexible structures are used to replace the previous rigid structures in the current bridge design.

When the vehicle passes through the bridge, it will shake, and the frequency of this shaking is disordered, so that the vibration frequency of the vehicle and the natural frequency of the bridge will not approach and overlap, thus avoiding resonance.

Resonance is also called "resonance" in mechanics and electricity. Refers to the phenomenon that an object amplifies its strength due to resonance. For example, when two identical springs are connected together, one of them will be simple harmonic motion and the other will be simple harmonic motion.

An important condition of resonance is to be elastic. When an object is subjected to external frequency, its frequency should be the same as or basically similar to the latter.

Generally speaking, most substances in the universe are elastic, from planets to atoms, almost all of them can vibrate at one or more natural frequencies.

Resonance is not only used very frequently in physics, but also one of the most common and frequent natural phenomena in the universe, so to some extent, it can even be said that resonance has produced the universe and everything in the world. Without resonance, there is no world. ?

Refer to the above content: Baidu Encyclopedia-resonance phenomenon