When the frequency of the driving force is close to or equal to the natural frequency of the object during the forced vibration of the object, the phenomenon that the amplitude of the object increases sharply is called * * * vibration. When people's walking frequency is the same as the natural vibration frequency of the bridge, * * vibration will occur, and there are often many people on the bridge in the army. If the * * vibration frequency of quick march is larger, theoretically the amplitude can reach infinity, leading to the collapse of the bridge.