Someone estimated the acceleration of the train with a watch. He observed it for 3min and found that the train had advanced 540M. After 2min, he observed it for 1min and found that the train had advanced 1620m If the train moves in a straight line with uniform acceleration within 6min, the speed of the train is? A.0.01m/s ² B.0.1m/s ² C.0.6m/s ² D.1.8m/s ²

Someone estimated the acceleration of the train with a watch. He observed it for 3min and found that the train had advanced 540M. After 2min, he observed it for 1min and found that the train had advanced 1620m If the train moves in a straight line with uniform acceleration within 6min, the speed of the train is? A.0.01m/s ² B.0.1m/s ² C.0.6m/s ² D.1.8m/s ²

Solution 1: there is a characteristic of uniform acceleration. In a time period, the speed at the midpoint of time is its average speed. Therefore, the train speed at 5:30 is 1620 / 60 = 27 m / S; Similarly, in one and a half minutes, the speed is 540 / 180 = 3 M / s, so a = (27-3) / (5.5-1.5) * 60 = 0.1 M / s * s. solution 2: from the beginning

1. The train leaving the station makes uniform acceleration and travels 540M in the first 1min, so how many M did it travel in the first 10s?

s=1/2*a*t^2
s1=1/2a*3600=540
s2=1/2*a*100=15m

The train starts from the station and moves in a straight line with uniform acceleration. If it advances 30m in the first 10 seconds, the acceleration is equal to the total advance of - m in the first 20 seconds, and the train at the end of the 20th second

s=0.5att
30=0.5a*10*10
a=0.6m/s2
The train advances in total within 20 seconds
S=0.5att=0.5*0.6*20*20=120m
Speed VT = at = 0.6 * 20 = 12m / S

A train is 200m long. It takes 100s to completely pass a bridge at the speed of 15m / s. what is the length of the bridge? By format, by format, by format

fifteen × 100-200=1300m

A train is 200m long and passes through a 1.6km bridge at a constant speed of 15m / s. find 1. All the time when the train passes through the bridge 2. All the time when the train is on the bridge

1. Train length L = 200m, speed v = 15m / s, bridge length s = 1600 m
All the required vehicles pass the bridge, and all the time is from the front of the vehicle to the end of the bridge until the rear of the vehicle leaves the end of the bridge
That is, total T = (L + s) / v = (200 + 1600) / 15 = 120 seconds
2. Because the length of the vehicle is less than the length of the bridge, when the rear of the vehicle just reaches the bridge head, the vehicle is all on the bridge until the front of the vehicle just reaches the bridge end. At other times, only a part of the vehicle is on the bridge
Therefore, the time for all vehicles on the bridge is t = (S-L) / v = (1600-200) / 15 = 93.3 seconds

A 200m long train passes through a 1.8km long bridge at a constant speed of 10m / s, (1) The time required for the train to pass the bridge completely is _, (2) The train has been running on the bridge all the time

(1) Distance of train passing the bridge s = s Bridge + s train = 1.8 × 1000m + 200m = 2000m, obtained from v = ST: T = SV = 2000m10m / S = 200s; (2) The distance of all trains running on the bridge s' = s bridge-s vehicle = 1.8 × 1000m-200m = 1600m, from v = ST: the time when the train runs on the bridge: t ′ = s ′ v