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The Say of the Week July 22, 2007

Posted by dorigo in games, humor, news, physics.

Tracks are dilating, trains run slower

(Original title on http://www.repubblica.it : “I binari si dilatano, treni piu’ lenti”).

Interesting concept. Of course the title means to say that given the high temperatures in Italy in this torrid July, tracks have become less safe for trains, which thus have to reduce their top speed. On the other hand, one could read the text to mean that trains take more time to reach destination because the total track length has increased! 😉 

Hmmm, wait! The wheels of the trains have also increased in size (they are equally made of steel). And indeed, the track length may change but the path length stays the same, if tracks dilatate to fill the gap between a piece and the next one. So in fact one would expect trains to cover the distance in less time… Also note that the speed of the train is read by instruments that measure the rotational speed of the wheels, assuming they have a constant diameter….

I have better stop now, lest I get accused of being a crackpot myself. These are days of suspicion.



1. Guess Who - July 22, 2007

… or maybe they are just days of sunstroke. 😉

2. dorigo - July 22, 2007

Also quite possible…

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