The curators over at the Exploratorium in San Francisco had an interesting question regarding the Golden Gate Bridge: It’s large, and made of metal, and so must expand and contract as it heats up during the day and cools off at night. But in what way, and by how much?
It turns out that as the sun heats the cables that suspend the roadway they expand and the deck lowers. As the sun sets and the bridge cools off, the deck rises back up. At the outdoor exploratorium, two miles away from the bridge, they installed a spotting scope trained on the bridge. The scope has a reticle that allows them to measure how much the bridge moves. The answer? The total excursion of the bridge deck, from hottest to coldest, is about 16 feet! The thermal mass of the bridge means that the position of the deck lags the change in temperature by about two hours.
Public TV station KQED produced a short video explaining the phenomenon. If you live in the Bay Area, or plan to visit, be sure to spend some time at the Exploratorium and visit their temperature-measuring spotting scope.
In our third annual contest, Design News and Allied Electronics are going to crown a winner in early 2016 for the best reader gadget submission this year, and once again, you, the readers, are the judges!
The Attack Dyno brings car enthusiasts an attack timer and dynamometer in a small, portable package with the ability to output vehicle torque, speed, horsepower, 1/4 mile times, 0-60 mph acceleration times, ambient air temperature, and more.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.