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scientific american

  1. NoneKnowNothingness

    Railroad Drawbridge Problem for Trigonometry Students

    A railroad drawbridge over a canal is to pivot upward, so boats can pass under it. For trig students this is a good problem. The end-plate of the bridge span, where it lifts away from the rest of the track, cannot be due vertical in its rest position. If it were, the plate would jam as the span...