Flying Trains

The first practical locomotive, a steam-driven behemoth designed in 1829 by the British engineer George Stephenson, managed to huff along with a full load of passengers at a speed of 24 miles per hour. Not bad for its time. 

Railroad steam has gone the way of the paddlewheel, replaced on the nation s commuter and cross-country railways by diesel oil and electricity. For decades, railways themselves have been in decline. Intercity passenger travel is dominated by the automobile and the plane. The truck is king of the road for freight hauling. Speed and convenience are the obsessions that have forced the train off to a siding, if not off the track altogether. 

recently there has been a renewed interest in rail alternatives—high-speed ones, of course, in keeping with the national preference. More specifically, the focus has centered on fast trains that would take advantage of developments in superconductivity and give us one of the most spectacular of all of its potential applications magnetically levitated trains, maglevs, that would literally fly between 

But even these fast trains have limitations. Chief among them is that they use conventional steel wheels against steel rails. The 170 mph that the French TGV can hit is probably the limit on such a conventional system. Larry Johnson explained it  

At speeds of about 120 miles per hour and greater, there is significant wear on both wheels and rails. Federal Railroad Administration standards for conventional freight trains and commuter trains allow relatively large discrepancies between the level of one rail and another—1.25 inches for 80 mph operations. However, the FRA standard drops to 0.5 inches [sic] for 120 mph operations. By comparison, the French TGV standard is 0.16 for the 170 mph portions of the system. Satisfying the standards for high-speed service is not impossible, but it is very expensive. 

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Such high-tech methods have not yet brought the new superconductors into the marketplace, but they most certainly give manufacturers what they need most from the warmer bulk ceramic materials—the forms that will carry frictionless electrical current and channel its perpetual, enormous power into everything from that wristwatch to flying trains. If the necessary properties can be built into the new superconductors, if the problems that still bedevil them are ironed out—and few, if any, believe that they will not be resolved—then superconductivity, once an exotic plaything, will, like the transistor and the laser, change the very way we live and work. 

Although government officials attempted to educate the public and military personnel about atomic civil defense, in retrospect these efforts seem hopelessly naive if not intentionally misleading. Army training films advised soldiers to keep their mouths closed while obser"ving atomic test blasts in order to not inhale radioactive flying dirt. Civil defense films used a friendly animated turtle to teach schoolchildren to duck and cover during a nuclear attack—that is, duck under their desks and cover their heads. Such measures, of course, would have offered pitiful protection to those in the blast zone. 

An everyday example illustrates the difference between state functions and path functions. The Daltons, who live in San Francisco, decide to visit relatives in Denver. They take different routes, as Figure shows. Mr. Dalton takes a train directly from San Francisco to Denver, but Ms. Dalton goes to Dallas for a business meeting and then flies from Dallas to Denver. The Daltons daughter drives to Los Angeles, where she catches a flight to Denver. 

When the fuze is unarmed the expl train is broken. The delay arming mechanism provides maximum safety for dive bombing as well as protection against detonation when the bomb is accidentally released from an aircraft flying at low altitude... 

Super Bee flies back and forth between the speeding trains... 

The Problem How far does a bee travel if it flies back and forth between trains that are approaching each other on the same track — one train traveling at 60 mph and the other traveling 75 mph — if the bee flies at 90 mph and, when it started this journey, the trains were 648 miles apart ... 

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