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 4 of 25.
RAEES said:
1 decade ago
Nusrath fathima solved method is better.
Chithu said:
1 decade ago
Very useful methods.
Rajan said:
1 decade ago
Periyasamy is perfectly correct and is the correct logic to solve the problem.
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.
Rohit said:
1 decade ago
For just above explanation, bridge end point means, departure point of bridge.
Nathy said:
1 decade ago
Sai's method of solving this problem is too simple and easy to understand. Thanks.
Mannsoorkhan said:
1 decade ago
sai your explanation is clear and better explanation thanks to all
Lokesh said:
1 decade ago
Actually bridge is a stationary object rite. So speed should be zero. Can u pls explain
Mukesh said:
1 decade ago
Given.....
train = 130m
speed = 45 km/hr or (75/6)m/s
time to cross bridge=30sec
Bcos the time is in sec thtat why we convert time in m/sec by multiplying and dividing 45 by 1000 and 3600 respectively
simple formula is distance=speed x time
=(75/6) x 30
=375 meters
now this distance is the distance which include train length also so less train length from this
=375-130
=245 meters
hence we get the ans
train = 130m
speed = 45 km/hr or (75/6)m/s
time to cross bridge=30sec
Bcos the time is in sec thtat why we convert time in m/sec by multiplying and dividing 45 by 1000 and 3600 respectively
simple formula is distance=speed x time
=(75/6) x 30
=375 meters
now this distance is the distance which include train length also so less train length from this
=375-130
=245 meters
hence we get the ans
Rajeev R T said:
1 decade ago
If the train is travelling 45 km per hr, then in one min.it can travel 750m, and in 1 sec it can travel 12.5m. then in 30 sec it can travel 375.00 m. As in 375m the length of the train is included, deduct the length of the train from the 375.00m, i.e 245.00m.
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