Freight railroads generally have operated the same way for more than a century: They wait for cargo and leave when customers are ready. Now railroads want to run more like commercial airlines, where departure times are set. Factories, farms, mines or mills need to be ready or miss their trips.
Called "precision-scheduled railroading," or PSR, this new concept is cascading through the industry. Under pressure from Wall Street to improve performance, Norfolk Southern and other large U.S. freight carriers, including Union Pacific Corp. and Kansas City Southern, are trying to revamp their networks to use fewer trains and hold them to tighter schedules. The moves have sparked a stock rally that has added tens of billions of dollars to railroad values in the past six months as investors anticipate lower costs and higher profits.
Calling all Railroad Tycoons...
(Score: 0) by Anonymous Coward on Friday April 05 2019, @08:47PM
Nope.
"Or, maybe the train just absorbs all the energy, resulting in some dents and crumpled metal. You're not going to measure any loss in speed. "
A human eyeball may not be able to see the loss in speed on the speedometer, but there will be a loss in speed. I wouldn't have made a fuss if you hadn't started with "maybe the train just absorbs all the energy" which makes it sound like there would be absolutely no change in speed. Conservation of momentum says that is incorrect, though your statement about no loss in speed is "basically" correct. Important to realize those distinctions.
Momentum in mass * velocity, so "total momentum" = (M1 x V1) + (M2 x V2)
The masses don't change and after the collision the car is traveling a lot faster than zero so the momentum was transferred from the train to the car, thus the train velocity decreases. The reason it is not very noticeable is because the mass and velocity of the train are so much higher that the momentum lost is a tiny percentage but it will be there.