>>The engine seemed to slowly come to a halt, I'm not sure why cars even further back got rammed into the back of the engine. Maybe there was another engine further back still pushing, or it was a downslope, or ? I was bracing for a nasty explosion when that tanker car came busting through.
>
>I just assumed that it was due to Newton's Law that objects in motion tend to stay in motion. That tanker car probably had a bit of inertia going.
>

Well, I'll be darned. All this time I have misunderstood the meaning of inertia. I thought it meant a lack of activity. As you clearly know, it can also mean maintaining velocity unless acted upon by an external force.

http://dictionary.reference.com/browse/inertia