Ikigai Daily
Menu
WonderEngineering lesson

The Tacoma Narrows Bridge in Washington State collapsed on 7 November 1940, four months after opening, when a wind of about 64 km/h set its light, flexible deck twisting until it tore apart. The disaster changed how engineers design long bridges against wind.

Tacoma, Washington, 7 November 1940

EngineeringScienceTechnologyHistory

The story behind the card

The bridge moved so much in the wind from the day it opened that locals nicknamed it Galloping Gertie. On the final morning the motion changed from up-and-down waves to a violent twisting, filmed by a local camera shop owner. No person died; a dog left in a stranded car was lost. The collapse is often blamed on resonance, but engineers now describe it as aeroelastic flutter: the twisting deck and the wind fed energy into each other. The investigation board included the aerodynamicist Theodore von Kármán. The replacement bridge, opened in 1950, used a deep, open truss that lets the wind pass through, and wind-tunnel tests became standard for long bridges.

Türkçe oku
Tacoma Narrows Köprüsü, ABD'nin Washington eyaletinde, açılışından yalnızca dört ay sonra, 7 Kasım 1940'ta çöktü: Saatte yaklaşık 64 kilometre hızla esen rüzgâr, köprünün hafif ve esnek yol kısmını kopana dek büktü. Bu felaket, mühendislerin uzun köprüleri rüzgâra karşı tasarlama biçimini değiştirdi.
Tacoma, Washington, 7 Kasım 1940

Köprü açıldığı günden itibaren rüzgârda öyle çok sallandı ki halk ona “Dörtnala Koşan Gertie” (Galloping Gertie) lakabını taktı. Son sabah aşağı yukarı dalgalanma, şiddetli bir burulmaya dönüştü; yerel bir fotoğrafçı dükkânının sahibi bu anları filme aldı. Kimse ölmedi; yolda kalan bir arabadaki köpek ise kurtarılamadı. Çöküş sık sık rezonansla açıklanır, ama mühendisler bugün bunu “aeroelastik çırpınma” (flutter) olarak tanımlar: Burulan köprü ile rüzgâr birbirine enerji aktararak hareketi büyüttü. İnceleme kurulunda aerodinamikçi Theodore von Kármán da vardı. 1950'de açılan yeni köprüde rüzgârın içinden geçebildiği derin, kafes kirişli bir yapı kullanıldı; uzun köprülerin rüzgâr tünelinde sınanması da standart hâle geldi.

Sources and further reading

Background reading: Tacoma Narrows Bridge (1940)
Get the mobile appAbout our cards

Related cards

These cards share a subject or reading mode with the card above.

WonderEngineering

A hypocaust was the Roman system of underfloor heating: a furnace sent hot air under a floor raised on small pillars and, in some buildings, up through hollow walls. It warmed baths and wealthy homes.

The name comes from Greek words meaning 'heated from below'. Under the floor stood rows of small brick or stone pillars, called pilae, and a furnace outside the room pushed hot air and smoke into this low space; hollow box tiles set into the walls could carry the heat upwards and out. Roman writers credited a wealthy businessman of the early 1st century BCE, Sergius Orata, with inventing heated 'hanging baths', but historians doubt he was the first to warm floors this way. The architect Vitruvius described how to build such baths late in the 1st century BCE, and the system spread across the empire, from Britain to North Africa. Keeping it going took a steady supply of fuel and enslaved workers or servants to tend the fires.

HypocaustRead card
WonderDesign

The Anglepoise desk lamp, designed in 1932 by the British engineer George Carwardine, stays at whatever angle you set it. Springs balance the weight of its jointed arms, so the shade moves with a light touch and then holds still.

Carwardine was a car designer and consultant who specialised in vehicle suspension, so he knew how springs could hold a load steady. He worked out a balance of springs and arms that let a lamp keep its position at almost any angle, and applied for a patent in July 1932. In 1934 he licensed the design to Herbert Terry and Sons, a spring maker in Redditch, and their four-spring model 1227, released in 1935 for use at home, proved very popular. In 1937 a Norwegian company, Luxo, began making its own version. A Luxo lamp later starred in Pixar's first short film, Luxo Jr. (1986), which is why a desk lamp still hops across the studio's logo.

Anglepoise lampRead card
WonderScience

A cloud chamber makes invisible charged particles visible: as one passes through air loaded with vapour, it leaves a trail of tiny droplets, like the vapour trail of a jet. Scottish physicist Charles Wilson invented it, and its photographs helped reveal new particles.

Wilson's idea began on the summit of Ben Nevis in 1894, where rings of coloured light around shadows cast on cloud made him want to recreate clouds in the laboratory. In his chamber, a sudden expansion cools moist air until the vapour is on the point of turning into droplets. A passing charged particle knocks electrons off air molecules, leaving a line of charged atoms, or ions, on which droplets form. He photographed the first tracks in 1911. With a magnet around the chamber the tracks curve, and the direction and tightness of each curve reveal a particle's charge and momentum. In 1932 Carl Anderson used such tracks to discover the positron, the first known particle of antimatter. Wilson shared the 1927 Nobel Prize in Physics for the chamber.

Cloud chamberRead card
WonderHistory

When Neil Armstrong radioed “Houston, Tranquility Base here. The Eagle has landed” on 20 July 1969, his words reached Earth about 1.3 seconds later. Radio waves travel at the speed of light, and the Moon is about 384,000 km (239,000 miles) away.

Eagle was the lunar module that carried Armstrong and Buzz Aldrin down to the surface. Light, and so radio, travels at almost 300,000 km per second. At the Moon's average distance of about 384,400 km, a signal takes roughly 1.28 seconds each way, so every exchange with Mission Control in Houston had a built-in pause of about 2.6 seconds before an answer could arrive. Large dish antennas at Goldstone in California and at Honeysuckle Creek and Parkes in Australia picked up the signals; the clearest pictures of the first steps came through Australia and were watched live by an estimated 600 million people. Before leaving, the crew set up a panel of reflectors on the surface. Scientists still fire lasers at it and time the light's return, which is how we know the Moon is drifting away from Earth by about 3.8 cm a year.

Ikigai DailyRead card
WonderTechnology

The Apollo Guidance Computer that steered astronauts to the Moon had about 4 kilobytes of rewritable memory and 72 kilobytes of permanent memory. Its programs were woven by hand into “rope memory”: a wire threaded through a tiny magnetic ring stored a 1, and a wire passing it by stored a 0.

Designed at the MIT Instrumentation Laboratory and built by Raytheon, the computer was one of the first to use silicon chips (integrated circuits) and fitted into about 28 litres. Its memory was counted in “words” of 16 bits, or binary digits: 2,048 rewritable and 36,864 permanent. During Apollo 11's descent on 20 July 1969 it flashed 1202 and 1201 alarms: a radar left on in case the landing had to be abandoned was stealing processing time and overloading it. Its operating system, designed by J. Halcombe Laning, dropped less urgent jobs and restarted in a moment while the landing programs kept running, so Mission Control told the crew to carry on. The flight software was written by a team led by Margaret Hamilton, who received the Presidential Medal of Freedom in 2016. Its power was similar to that of the first home computers of the late 1970s.

Ikigai DailyRead card
Next card in the archiveMachu Picchu, a 15th-century Inca estate on a ridge high in the Peruvian Andes, stands on hundreds of stone terraces. They hold the steep soil in place, drain away heavy rain and gave the Inca room to grow crops.Read next →