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As shown in the figure, a railway bridge is 400m long. A person walks on the bridge. When he walks 190m away from the bridge head in front, he finds a train coming in the face. The train speed is 40m / s and the train is 800m away from the bridge head in front. How fast can the person run at least to leave the railway bridge safely?
Run forward: ∵ train speed V1 = 40 M / s. The distance between the train and the front bridge head is S1 = 800m. ‡ from the speed formula v = ST: T1 = s1v1 = 800m40 M / S = 20s. ‡ the maximum time for pedestrians to leave the railway bridge safely is T2 = T1 = 20s. ∵ the distance between pedestrians and the front bridge head is 190m, that is, S2 = 190m. ∵ pedestrians leave the railway bridge safely to
A railway bridge is 400m long. A person walks on the bridge. When he walks 190m away from the bridge head in front, he finds a train coming in the face. The speed of the train is 4cm / s and the train is 800m away from the bridge head in front. How fast can the person run at least to leave the railway bridge safely?
190/800/0.04=0.0095 m/s=0.95cm/s
A railway bridge is 400 meters long. A person walks on the railway bridge. When he walks 220 meters away from the bridge head in front, he finds a train coming up at a speed of 40 meters / s. The train is 800 meters away from the bridge head in front. The person can turn and run at a speed of at least () meters / s in order to leave the railway bridge safely Be accurate
Set the speed to v0
（800+400）/40=（400-220）/v0
The solution is V0 = 6 m / s
On a track, two trains pass each other. If train a is 180 meters long and train B is 160 meters long, and the passing time of the two trains is 1.7 seconds, it is known that train a is 5 meters faster than train B per second, what are the speeds of train a and train B respectively?
A vehicle speed = [(180 + 160) ÷ 1.7 + 5] ÷ 2 = 102.5 M / S
B vehicle speed = [(180 + 160) ÷ 1.7-5] ÷ 2 = 97.5m/s
On the two track railway, two trains cross each other. If train a is 180m long and train B is 160m long, the passing time of two trains is 1.7 seconds. Train a is 5m faster than train B every second On a two track railway, two trains cross each other. If the total length of train a is 180m and the total length of train B is 160m, the passing time of the two trains is 1.7 seconds. It is known that the speed of train a is 5m faster than that of train B, what are the speeds of train a and train B respectively
[(180 + 160) ÷ 1.7 + 5] ÷ 2 = 12.5 M / s, speed of train a
[(180 + 160) ÷ 1.7-5] ÷ 2 = 7.5m/s, speed of train B
On the double track railway, two trains pass head-on. The speed of train a is 20 m / s, the speed of train B is 24 m / s, the length of train a is 180 m, and the length of train B is 172 M. calculate the wrong train
Since the formula for passing is (car length a + car length b) / (car speed a + car speed b) = passing time, the formula is (180 + 172) / (20 + 24) = 8 seconds
RELATED INFORMATIONS
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