The speed of the train is 10.8km/h when it passes a road sign, and 54km / h after 1min. How long does it take for the train to reach 64.8km/h?

If 10.8km/h = 3m / s, 54km / h = 15m / s, 64.8km/h = 18m / s, the acceleration of the train is a = V2 − v1t = 15 − 360m / S2 = 0.2m/s2, and the time t '= V3 − V2a = 18 − 150.2s = 15s

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