A1000 kg train car traveling at 12 m/s on a level track has 400 kg of sand dumped, vertically, into it. what is the final speed of the train car after the sand is dumped into it? ignore friction

Aproduction line at v. j. sugumaran's machine shop has three stations. the first station can process a unit in 7 minutes. the second station has two identical machines, each of which can process a unit in 16 minutes (each unit only needs to be processed on one of the two machines). the third station can process a unit in 10 minutes. ▼ is the bottleneck station, with a bottleneck time of nothing minutes per unit (enter your response as a whole number).