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 10 of 25.
Subramanyam subbu said:
1 decade ago
distance=speed*time
assume length of bridge as x meters
here distance=(length of bridge+length of train)
x+130=45*(5/18)
[ 5/18 indictes conversion of km/hr to m/sec)
we get x= 245 m i.e length of the bridge
assume length of bridge as x meters
here distance=(length of bridge+length of train)
x+130=45*(5/18)
[ 5/18 indictes conversion of km/hr to m/sec)
we get x= 245 m i.e length of the bridge
Vinu said:
1 decade ago
I've a doubt, if the bridge length is greater than the length of the train, then the train need to travel twice it's length + (bridge length-train length) to cross the bridge, why that factor is not considering in this problem?
RITESH said:
1 decade ago
I want to ask a simple question, how was to come 25/2 ? please send this answer ASAP.
Madhu said:
1 decade ago
We should convert km/hr to m/sec, so we should multiply the 45km/hr by 5/18,then we get 25m/sec.
Sara said:
1 decade ago
Total distance of bridge is 45Km/hr*(30/360)hrs =45/12Kms
Distance in metres = (45/12)*100 =375 Metres
Distance covered = 375M -130M =245M
I believe this is the quickest way given the time allocated in such assessments.
Distance in metres = (45/12)*100 =375 Metres
Distance covered = 375M -130M =245M
I believe this is the quickest way given the time allocated in such assessments.
BaluRajasekaran said:
1 decade ago
45 km/hr = 12.5 m/s
then the train travel 375 m in 30 seconds
[i.e] 12.5[speed] * 30[total time to reach] = 375[this is the time the train completely out of the bridge]
then the length of bridge is 375 - 130[length of train]= 245
then the train travel 375 m in 30 seconds
[i.e] 12.5[speed] * 30[total time to reach] = 375[this is the time the train completely out of the bridge]
then the length of bridge is 375 - 130[length of train]= 245
Kriti said:
1 decade ago
@VINU
Exactly that would be the total distance travelled by train in 30 sec
Exactly that would be the total distance travelled by train in 30 sec
Kriti said:
1 decade ago
[][][][]```````````````[][][][]
```````````````
Train Bridge Train(and timer
(and timer stops here)
starts here)
<------------------------>
This is distance travelled by train in 30 sec (375m)
<--------------><-------->
Lenght of bridge Lenght of train (130m)
Lenght of bridge = distance travelled in 30 sec - lenght of train
Hence proved. : )
```````````````
Train Bridge Train(and timer
(and timer stops here)
starts here)
<------------------------>
This is distance travelled by train in 30 sec (375m)
<--------------><-------->
Lenght of bridge Lenght of train (130m)
Lenght of bridge = distance travelled in 30 sec - lenght of train
Hence proved. : )
Shahul hameed.M said:
1 decade ago
Am telling the easy way to solve this problem......
in basic formula is
L=speed*time
here we wanna 2 find length of the bridge so,
L1+L2=speed *time(L1=length of the train,L2=length of the bridge)v can get d ans easily....
in basic formula is
L=speed*time
here we wanna 2 find length of the bridge so,
L1+L2=speed *time(L1=length of the train,L2=length of the bridge)v can get d ans easily....
Mayu said:
1 decade ago
Yes shahul I like your tact to solve this problem.
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