Matt Parker Quotes That Will Inspire You to Live Your Best Life

1. A crude analogy for resonance is that of a pendulum, often modeled as a child in a swing. If you are charged with pushing the child and you just thrust your arms out at random intervals, you will not do very well: you’d hit the child coming toward you and slow the swing down as often as you’d give the swing a push as it’s going away and speed it up. Even a regular pushing rate that did not match the movement of the swing would leave you pushing empty air most of the time. Only if you push exactly at the rate that matches when the child is directly in front of you and starting their descent will you achieve success. When the timing of your effort matches the frequency the swing is moving at, each push adds a little more energy into the system. Humble Pi: A Comedy of Maths Errors

2. People stepping up and down should not be a problem, and even the 1-Hertz sideways back-and-forth movement of humans walking should not have been a problem, as everyone is likely to be stepping at different times. For anyone pushing with their right foot, another person would be pushing with their left, and all the forces would pretty much cancel each other out. This sideways resonance would only be a problem if enough people walked perfectly in step. This is the synchronous in synchronous lateral excitation from pedestrians. On the Millennium Bridge, people did start to walk in step, because the movement of the bridge affected the rhythm at which they were walking. This formed a feedback loop: people stepping in sync caused the bridge to move more, and the bridge moving caused more people to step in sync. Humble Pi: A Comedy of Maths Errors

3. The sixty-story John Hancock Tower was built in Boston in the 1970s, and it was discovered to have an unexpected torsional instability. The interplay of the wind between the surrounding buildings and the tower itself was causing it to twist. Despite being designed in line with current building codes, torsional instability found a way to twist the building, and people on the top floors started feeling seasick. Once again, it was tuned mass dampers to the rescue! Lumps of lead weighing 330 tons were put in vats of oil on opposite ends of the fifty-eighth floor. Attached to the building by springs, the lead weights damp any twisting motion and keep the movement below noticeable levels. Humble Pi: A Comedy of Maths Errors