A locomotive of mass 2.0×105kg pulls five identical railcars, each of mass 4.0×104kg. The locomotive’s drive wheels exert a forward force of 1.2×105N on the track. Rolling resistance of 1.0×104N acts on each railcar, while resistance on the locomotive is negligible. What is the magnitude of the train’s acceleration?
a) 0.30m/s2
b) 0.18m/s2
c) 0.15m/s2
d) 0.43m/s2