Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 3)
3.
The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:
Answer: Option
Explanation:
| Speed = |  |
45 x | 5 |  m/sec |
= | |
25 | m/sec. |
| 18 | 2 |
Time = 30 sec.
Let the length of bridge be x metres.
| Then, | 130 + x | = | 25 |
| 30 | 2 |
2(130 + x) = 750
x = 245 m.
Video Explanation: https://youtu.be/M_d8WufJWKc
Discussion:
245 comments Page 22 of 25.
Rohit said:
1 decade ago
For just above explanation, bridge end point means, departure point of bridge.
Rohit said:
1 decade ago
< (end-point) train (start-point) >EntreR-----[BRIDGE]---< (end point) trian (start-point) >. When train end point meets bridge end point, according to this time is given 30 sec. So we have to add bridge length + train's length as total distance travelled in 30 sec. Two different way are given to solve this prblm.
Rajan said:
1 decade ago
Periyasamy is perfectly correct and is the correct logic to solve the problem.
Chithu said:
1 decade ago
Very useful methods.
RAEES said:
1 decade ago
Nusrath fathima solved method is better.
Periyasamy v said:
1 decade ago
I solved my own speed of the train 45km/hr,then change into 45000m/hr,then chang into per second (45000/3600)=12.5 m/sec,then multiple with 30sec,(12.5*30)=375, then mins the train length 375-130=245 i think this s correct......
Murali said:
1 decade ago
Hai! Janani while converting the distance it will come how means.
I) if you convert km/hr into m/sec then multiplies with "5/18".
Ii) if you convert m/sec into km/hr then multiplies with "18/5".
In this way, above problem the train speed is convert into the km/hr into m/sec. (because the answer is given in the form of meters).
Like this 5/18 will come.
I) if you convert km/hr into m/sec then multiplies with "5/18".
Ii) if you convert m/sec into km/hr then multiplies with "18/5".
In this way, above problem the train speed is convert into the km/hr into m/sec. (because the answer is given in the form of meters).
Like this 5/18 will come.
Murali said:
1 decade ago
@Mannu.
Here we know only length of the train. We have to find the length of the bridge. We know the formula"s=d/t".
Here distance is "L1+L2".
Therefore "s= (L1+L2) /t".
Now we will get the answer.
By adding two distance only we will find the one distance (if you know the one distance then find the length of the train).
Here we know only length of the train. We have to find the length of the bridge. We know the formula"s=d/t".
Here distance is "L1+L2".
Therefore "s= (L1+L2) /t".
Now we will get the answer.
By adding two distance only we will find the one distance (if you know the one distance then find the length of the train).
Janani said:
1 decade ago
How 5/18 came?plz xplain this..
Mannu said:
1 decade ago
What is the significance of train's length. Since the train crossed the bridge so distance should be of the bridge only. Why that bridge and train added?
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