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How long does it take for a 120cm long train to pass through a 300m long tunnel at the speed of 54
LZ, you are such a girl. A 120cm long train? There is no ordinary bicycle long train yet. The [toy car] can run at a speed of 54 [but I don't know whether it's kilometers or miles]. Is it 54 meters per hour?
You can't answer this question
I can't help but go with two points
It takes 20 s for a train to travel at a constant speed through a 300 m tunnel There is a lamp on the top of the tunnel, which emits light vertically downward. The light shines on the train for 10s. According to the above data, can you calculate the length of the train? Please explain the detailed reasons!
This problem is a series of univariate linear equations with vehicle speed as an equal quantity
Set the train length as X
(300+x)/20=x/10
When the train passes through a 300 meter tunnel, it actually runs 300 meters, plus the length of the body. When the light shines on the car for 10 seconds, it runs the whole length of the body in 10 seconds
The calculated train length is 300 (m)
It takes 2.5min for a 300m long train to pass through a tunnel at a constant speed of 36km / h, so what is the length of the tunnel? What is the running time of all trains in the tunnel?
36km / h = 10m / s, 2.5min = 150s
Setting: the tunnel length is x M
（300+X）=10 × 150, x, i.e. the tunnel length is 1200 meters
(1200-300) ÷ 10 = 90 seconds, that is, the time for the train to be completely in the tunnel is 90 seconds
The tunnel is 550 meters long and a train carriage is 50 meters long. It is running at a uniform speed of 36 km / h. The speed of a passenger in the carriage is 1 meter / s. when the train passes through the tunnel, the time for passengers to pass through the tunnel is at least () A. 5 seconds B. 50 seconds C. 55 seconds D. 60 seconds
VCAR = 36km / h = 36 × one
3.6m/s=10m/s，
The minimum time for passengers to pass through the tunnel is t,
Then the distance traveled by a person: s person = V person t,
Distance traveled by train: S = v = t,
As shown in the figure below, s person + s Vehicle = l tunnel,
I.e. 1m / S × t+10m/s × t=550m，
The solution is: T = 50s
S person = V person t = 1m / S × 50s = 50m, it can be seen that the passengers just walked to the front of the car
Therefore, B
A railway bridge has a total length of 1200 meters. It takes 19 seconds for a train to cross the bridge and 15 seconds for a train to cross a roadside telegraph pole. Then the total length of the train is meters
The distance across the bridge is bridge length + vehicle length, and the time is 19 seconds
It takes 15 seconds to drive past the pole
It shows that it takes 4 seconds to cross the bridge with a length of 1200 meters, that is, the speed is 300 meters per second
The vehicle length is 300 * 15 = 4500 meters
A train passes through two railway bridges at a speed of 600 meters per minute. It takes five seconds to cross the second railway bridge than the first railway bridge, It is known that the length of the second railway bridge is 50 meters less than twice the length of the first railway bridge. Find the length of the first railway bridge. (solve with one-dimensional first-order equation)
Train speed conversion: 600m / min = 10m / S
Assuming that the length of the first railway bridge is x, the length of the second railway bridge is 2x-50. According to the given conditions, the following formula is obtained:
x÷10=（（2x-50）÷10）-5
Solve the equation: x = 100m
The first railway bridge is 100 meters long
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