Could a heavy object cause a train derailment?

Duke C.

[scrabblehack]

Pounds of mass can be abbreviated as lbm; pounds of force can be abbreviated lbf.

1 lbm-ft/s^2 = 1 poundal.
1 lbf = 1 slug-ft/s^2

http://en.wikipedia.org/wiki/Slug_%28mass%29
http://en.wikipedia.org/wiki/Poundal

[trebb]

During a traffic safety class (military) a train engineer speaks about his encounters with cars on the tracks - he said he never felt the impact of any of them....Don’t know if your calculations for the object are correct, but don’t forget the other side of the equation....

[schurmann]

“...Where I went wrong was in assuming the formula ke = 0.5*m*v**2 actually yielded foot-pounds. ...”

Getting the units correct is a recurring nightmare for scientists and engineers. So are American/English measurement conversions; metric is much simpler. The only reason the Anglophone system hangs on at all is because of early British and American dominance in aeronautics and astronautics.

Considerable chunks of my struggle through higher education were taken up by aeronautical engineering. I’d estimate that during my first trimester in grad school (courtesy of USAF), I spent 1/4 to 1/3 of my time converting from one measurement to another.

[schurmann]

” ... don’t forget the other side of the equation....”

“The other side” barely stirs the dust settling into the paint scratches, when it comes to understanding what happens when one object hits another.

I have wished - usually after days of head-scratching - that there was only a single equation to deal with.

Interested forum members are invited to perform a websearch on the acronym SURVIAC.

[trebb]

Did the search on SURVIAC - interesting info.

My point was that the cases where they had objects hitting the trains left dents or cracked windows vs. a catastrophic hit. It would take one hell of an impact with something large enough to not just punch a hole to knock an engine off the rails. Smaller items affixed to the rails would likely be able to cause it to leave them, but a pure impact needs to take into account the inertia and mass of the engine which is "substantial". The damage would be massive.

I made an earlier "tongue-in-cheek" comment about how they might try to use the objects as an excuse to lessen their liability and that it could only be valid if the engineer yanked the steering wheel hard enough to throw his train off the rails....