This is why engineering is important

This is a classic in the engineering field:



By pushing a swing at the right moment you can add more energy, and thus more height. By pushing again and again, the swing can go higher and higher. This is a well known issue with bridges built in windy places.

The bridge became a swing and was destroyed by the wind pushing and pushing.

I heard an explanation about what happened with the first Tacoma Narrows bridge. The engineers for the bridge about the problem, and they compensated for the harmonics by designing the bridge to dampen out the oscillation. But they only thought about first order oscillation.


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