As well as the dangers of placing the penny when there is a train barreling down the tracks, I’ve also heard that rather than getting squashed the penny could go shooting out in a random direction. Probably not a lethal velocity but at a “you could put your eye out” velocity.
I would put it like this:
Any time you have a multi-ton iron machine that can come into contact with a fragile human body, the results of most any kind of contact is almost always going to impact the human in a very nasty way. Bottom line? If a human comes into contact with a train, they will almost def and for sure be sorry. Very, very sorry. Or … they will be dead in which case theirr family will be hurt very badly hurt (emotionally speaking). Bottom line? It’s just not a good idea.
Have you ever seen one of those “crazes” where youths go running along the top of a moving train? Or go jumping on the tops of moving elevator cars? Even better … have you ever seen pictures of what a human body looks like when it’s been squashed by a train or flattened by an elevator? From what I understand, it doesn’t look at all human any longer. It wouldn’t be a very nice thing to happen to one of your family members. It would be best to keep your family members out of contact with moving trains or elevator cars. The consequences could be very, very squashy. And very very flat. I am pert near sure that your mommy wouldn’t like it and it would make her cry for many, many years.
Would you really like to do that to your mommy?
Well, it must have made a hell of a bump. :dubious:
I didn’t know that Camden was issuing its own currency. 
Apparently, the idea that, while pennies squash, nickles will derail the train is only an urban legend.
It was surprisingly loud for just a penny.
I’ve run over hundreds or thousands of pennies, in everything from a 25-ton teapot narrow-gauge locomotive to the modern P42’s on Amtrak, and you can’t tell any difference in terms of sound or feel when you go over one (or a series of them.)
Sometimes we’d see the people put them on the rails, and they’d get a glare for trespassing and/or making it seem as if they’re going to run out in front of us and get hit, which, again, isn’t a fun way to make your day. But there’s no ‘bump’ for the crew on board.
With human beings (or cows) there isn’t any physical sensation when the train strikes them, but because of the acoustics of a modern locomotive (think lots of sheet metal over a skeleton) the sound resonates through the cab. And once you’ve seen what remains of the victim after the fact, ANY potential trespasser is likely to give you a pucker-up moment.
And, crews generally get only the rest of the day off, or up to 3 days off max. It…takes a bit longer than that to begin to come to terms with a trespasser strike.
How about if you dropped a train off the Empire State Building? 
Silly DrDeth. Everyone knows that the air currents up there are such that they’d just blow the train back up onto the balcony.
Thanks Chronos. I was beginning to despair of anyone actually answering the question this being GQ and all.
What if you first place the penny on a frictionless treadmill…
It just so happens there’s a very active RR track not 10 paces from the back door of the studio I work out from.
If I’m feeling particularly bored, I might plop down at least a roll of pennies on each rail—a penny a foot—and see what happens.
If I do, I’ll record it and post a link here.
I tried using scotch tape and the effect was exactly the same as if I had not used anything.