[CBQ] Railroad Freight Cars Moving on Their Own

["smokyjoe66" <js08ws62@sbcglobal.net>]

It seems to me that everyone on this list is here because we admire, love, and 
are generally curious about all the aspects of railroading.  So, this question, 
though off-topic, might be of general interest to all, and of specific interest 
to those who know physics.

Railroading began and continues to be a popular and effective way of moving 
freight because a rolling steel wheel on a steel rail is very efficient. I have 
seen reports that an 8- wheel freight car rests on less than 2 square inches. 
And, it is steel on steel -  little friction. Moreover, I am sure all of us 
have witnessed the very long distances that a very slow moving freight car can 
roll on its own. It is phenomenal.   So? here's a theoretical question:

If an ordinary, empty, boxcar resting on 2 roller-bearing 4-wheel trucks was 
given a 50 mile an hour push on a perfectly level, perfectly straight railroad 
track on a windless day, how far would it go before stopping on its own? 

It also would be interesting to hear some of your stories known from personal 
experience regarding long distances rolled by railroad cars moving on their 
own. Another phenomenon worthy of comment would be just how silently they roll. 
I'm sure many have stories about that, too.




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