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:
247 comments Page 21 of 25.
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?
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
Viji said:
1 decade ago
Vijay kumar your explanation is quite simple and understandable. Thank you.
Anshul patel said:
1 decade ago
Amasing solutions and discussion by you guys but 1 thing I got in mind while coming through few examples is that if some1 is new in solving this type of problems then please draw 1 rough imaginary sketch and then try to solve this type of examples I prefer it to be more easy.
Mathsfobia said:
1 decade ago
Nice explanation survjt.
DGEERAJ said:
1 decade ago
Nusrat has right formula to solve this.
Sarvjeet said:
1 decade ago
Length of the train= 130.
Speed of the train = 45km/hr.
time=30sec.
lengthof bridge = x+length of train.
x+length of train = Speed of the train *time.
x+130=45*5/18*30.
x+130 =375
x=375-130
x=245
Speed of the train = 45km/hr.
time=30sec.
lengthof bridge = x+length of train.
x+length of train = Speed of the train *time.
x+130=45*5/18*30.
x+130 =375
x=375-130
x=245
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.
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
Lokesh said:
1 decade ago
Actually bridge is a stationary object rite. So speed should be zero. Can u pls explain
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