La'al ratty: the power of steam

We visited the Ravenglass and Eskdale Railway. We were amazed to see the big load being pulled by such a small engine. I counted 10 carriages. You could fit 20 people on each. Say an adult was 60kg. 20x60x10 = 24000kg. Now say eaxh carriage had a mass of 1 tonne - there's another 10000kg. I timed the train as it accelerated out of the station. I estimated 25 metres in 45 seconds, by counting carriage lengths. Using the suvat equations of uniformly accelerated motion, I got an acceleration of 0.025 metres per second per second. Using Newton's 2nd Law equation F=ma gives a force of about 550N. My weight is not much more than this. The problem is that I've discounted friction. The implication would be that if you hung me over a void on a rope over a pulley, I'd get the train moving. That wouldn't happen because of the friction. Also, the acceleration was probably bigger - I think the train had reached a steady speed well before the 25 metres was up. Finally, the carriages might be more than 1 tonne each.