Q- A railroad hopper car weighs 50000 kg when empty and contains 50000 kg of coal. As it coasts along the track at 9 m/s the hopper opens and steadily releases all the coal onto a platform below the rails over a period of 6 s.
a) How fast does the car travel after all the coal is dumped?
b) What was the momentum absorbed by the platform?
c) If the coal comes to rest 1 second after the dumping is finished, what was the average horizontal force on the platform?
d) If the coal fell 2 m, what was the total energy converted to heat in the process of the coal coming to rest?
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