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A train advances at the speed of 20m / s and whistles 1800m away from a tunnel entrance. Q: when the driver hears the echo, how far is the locomotive from the tunnel entrance
20+340=360
1800*2=3600
3600/360=10
20*10=200
1800-200=1600m
A train advances at a speed of 20m / s and whistles 500m away from a tunnel entrance. Q: when the driver hears the echo, how far is the locomotive from the tunnel entrance Set the sound propagation speed as 340 m / s
The sound has passed when it meets the tunnel entrance t = 500 / 340 = 25 / 17s
During this period, the train went S1 = 20 * t = 500 / 17m
S2 = 500-s1 = 8000 / 17m away from the tunnel entrance
When the train heard the echo, it passed T1 = S2 / 360 = 200 / 153 s
The sound propagated 340 * T1 = 4000 / 9 = 444m during this period
That is, the distance between the train and the tunnel
A 150 meter long train passes through a 600 meter tunnel at a speed of 15 meters per second. From the moment the train enters the tunnel mouth, the time required for the train to completely pass through the tunnel is () A. 60 seconds B. 30 seconds C. 40 seconds D. 50 seconds
Suppose it takes x seconds for the train to pass through the tunnel completely,
Then the equation is obtained: 15x = 600 + 150,
The solution is: x = 50,
A: it takes 50 seconds for the train to pass through the tunnel completely
Therefore, D
A 150 meter long train passes through a 600 meter tunnel at a speed of 15 meters per second. From the moment the train enters the tunnel mouth, the time required for the train to completely pass through the tunnel is () A. 60 seconds B. 30 seconds C. 40 seconds D. 50 seconds
Suppose it takes x seconds for the train to pass through the tunnel completely,
Then the equation is obtained: 15x = 600 + 150,
The solution is: x = 50,
A: it takes 50 seconds for the train to pass through the tunnel completely
Therefore, D
A 200 meter long train moves in a straight line at a uniform speed. The time it takes for the whole train to pass through the 1.8 kilometer long bridge is 100 seconds. So, how fast is the train traveling?
The distance traveled by the whole train across the bridge = bridge length + train length = 1800m + 200m = 2000m, t = 100s,
Substitute the velocity formula v = s
t=2000
100=20m/s；
A: the speed of this train is 20 meters per second
If a 200 meter train runs at a constant speed of 20 meters per second, how many seconds does it take for the train to completely pass through the 1.8 kilometer long bridge?
(1800+200)/20=100s
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