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:
249 comments Page 18 of 25.
Vidya said:
10 years ago
1 hour = 60 min.
1 min = 60 sec.
1 km = 1000 m.
Km per hour to m per sec:
1 km/1 hour = 1000 m/60*60 sec.
=> 1 kmph = 1000/3600 sec = 5/18 sec.
1 min = 60 sec.
1 km = 1000 m.
Km per hour to m per sec:
1 km/1 hour = 1000 m/60*60 sec.
=> 1 kmph = 1000/3600 sec = 5/18 sec.
Kiran said:
10 years ago
Hi @Anjaneyulu,
5/18 is just to convert the speed km/hr into m/s.
5/18 is just to convert the speed km/hr into m/s.
Naveen Kumawat said:
10 years ago
Speed of train = 45 km/hr.
Or (45*100) m/(1*60*60) sec = (25/2) m/sec.
#----130m------>|________x meter_____________|cross in 30sec.
Train bridge.
|<--------------------130m+x---------------->|.
//# is the tail of train from where the crossing of bridge is observed.
So the total distance from # to end of the bridge is (130m+x).
And from distance formula:
Distance/Time = Speed.
i.e (130+x)/30 = 25/2.
Solving we get 245 m.
Or (45*100) m/(1*60*60) sec = (25/2) m/sec.
#----130m------>|________x meter_____________|cross in 30sec.
Train bridge.
|<--------------------130m+x---------------->|.
//# is the tail of train from where the crossing of bridge is observed.
So the total distance from # to end of the bridge is (130m+x).
And from distance formula:
Distance/Time = Speed.
i.e (130+x)/30 = 25/2.
Solving we get 245 m.
Kamal Jeet said:
9 years ago
Simple Solution!
First of All change 45 KM/HR = 45000 m/s.
Travelling in 60 sec = 45000/60 = 750.
Now for 30 sec = 750/2 = 375.
Last subtract train length = 375 - 130 = 245.
I hope, this helps you!
First of All change 45 KM/HR = 45000 m/s.
Travelling in 60 sec = 45000/60 = 750.
Now for 30 sec = 750/2 = 375.
Last subtract train length = 375 - 130 = 245.
I hope, this helps you!
Rekha said:
9 years ago
Hii @Sai.
Why did you subtract the two things that is length and speed?
Why did you subtract the two things that is length and speed?
Maanvi said:
9 years ago
@Naveen Kumawat.
Nice description to understand the problem.
Nice description to understand the problem.
Nowsath said:
9 years ago
I have a simple method.
45 * 5/18 equal 12.5 m/s.
Then,
12.5 = x + 130/30 then,
12.5 * 30 = 375.
So,
375 - 130 = 245.
Therefore, x equal 245.
45 * 5/18 equal 12.5 m/s.
Then,
12.5 = x + 130/30 then,
12.5 * 30 = 375.
So,
375 - 130 = 245.
Therefore, x equal 245.
Sandeep said:
9 years ago
It is easy,
Train length = 130mtr,
Speed = 45km/hr,
Time = 30sec.
First:-
Converting the speed:- 45*5/18 = 12.5,
Then, total distance = speed * time.
= 12.5 * 30 = 375.
Therefore, the length of bridge = 375 - 130 = 245.
Train length = 130mtr,
Speed = 45km/hr,
Time = 30sec.
First:-
Converting the speed:- 45*5/18 = 12.5,
Then, total distance = speed * time.
= 12.5 * 30 = 375.
Therefore, the length of bridge = 375 - 130 = 245.
Sidhartha said:
9 years ago
The train has to cover twice it's own length and the length of the bridge to cross the bridge so the answer provided is wrong.
It has to be 2x + 130 = 375.
Hence 2x = 245.
X = 122.50m = length of the train.
It has to be 2x + 130 = 375.
Hence 2x = 245.
X = 122.50m = length of the train.
Emme Naresh said:
9 years ago
Distance = speed/time;.
Let us bridge length = x say, train travelling distance = 130 m.
The total distance is = x + 130,
Speed = 25/2; time = 30sec.
X + 130 = (25/2) 30,
X = 375 - 130 = 245.
Let us bridge length = x say, train travelling distance = 130 m.
The total distance is = x + 130,
Speed = 25/2; time = 30sec.
X + 130 = (25/2) 30,
X = 375 - 130 = 245.
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