[QUOTE=Eyer8]
(Re preventing a train from moving with a penny)I’m not sure I buy this… Got a cite? Or how about just a cite giving me the torque imparted by a locomotive at the wheel, the coefficient of static friction for steel on steel, the radius of the wheel, and the mass of the locomotive… Do I need anything else?
[/QUOTE]
This has come up before, and IIRC, the primary reason you can keep a train from starting with a penny on the tracks is railroad policy - if the engineer can’t get rolling in second notch on the throttle, they’re to stop and investigate the problem.
[QUOTE=Chronos]
Unfortunately, the only cite I have is the word of my uncle, who used to hang around railyards a lot in his irresponsible youth. But even if a penny won’t do the trick, any MIT student ought to be able to figure out something he can throw in front of the wheels to temporarily stop a streetcar.Certainly the thickness of a penny, probably also the compressive strength of copper, and maybe the coefficient of dynamic friction. If the problem is still standing as of tomorrow afternoon, I’ll have a go at it, too.
[/QUOTE]
Sounds like a good problem to do over Saturday morning coffee… I’m sure I can find all this by googling.
[QUOTE=Mangetout]
Dunno; you might be right, but to me it seems just like excessive editing and thrifty re-use of material.
[/QUOTE]
Brainiac is pretty bad about this. Probably half the show is reused filler around segments. It’s really hard to watch multiple episodes in a row.
Well, nowadays they won’t be pure copper, but back at the time my uncle would have acquired this information, they were. If the choo-choo would be able to squash a copper coin (which I presume is easier than zinc), I’d be willing to call this a busted myth.
Addendum: I just called my uncle, to confirm the story. He said that, first of all, he only ever heard it about steam locomotives, and he doesn’t know whether it would work on a modern diesel. Second, he never actually personally saw it done; he just heard from others who claimed to have done it. So we’re well into FOAF territory here.