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:
252 comments Page 5 of 26.
Sivakumar.s said:
1 decade ago
Train 130 meters long. Travel 45 km/hr.
To convert m/s = 25/2.
So 2 second train will move 25 meter. So 30 second means.
2*15 = 30 second.
25*15 = 375.
So train travelling 375 meters to reduce the train meters.
375-130 = 245.
So the bridge meter is 245 meters.
To convert m/s = 25/2.
So 2 second train will move 25 meter. So 30 second means.
2*15 = 30 second.
25*15 = 375.
So train travelling 375 meters to reduce the train meters.
375-130 = 245.
So the bridge meter is 245 meters.
(1)
ARYAN said:
7 years ago
Length of the train = 130m.
speed =45km/h so, 45/3.6=12.5.
12.5*time=12.5*30=375m.
length of the bridge = [375-130] = 245m ANS.
speed =45km/h so, 45/3.6=12.5.
12.5*time=12.5*30=375m.
length of the bridge = [375-130] = 245m ANS.
(1)
Banda said:
7 years ago
Hi, Good explanation. Thanks all.
(1)
Ahmad said:
7 years ago
(130 + x)/30 = 25/2.
What is meant by this?
What is meant by this?
(1)
Mahamud said:
6 years ago
Can you explain, How come25/2?
(1)
Priyanka Priyadarshini Samal said:
6 years ago
We have to calculate speed.
Speed = 45*5/18=25/2 m/s.
Time is given t= 30 sec.
Let's find the length of the bridge,
Let the length of the bridge is X.
And whenever a train crosses the bridge then the total distance covered by the train is the length of the bridge +it's own length (train's length),
According to the motion's 1st law distance or displacement = speed *time.
X+130 =25/2*30.
2(X+130)=750.
2X+260= 750.
X= (750-260)/2= 245m.
Speed = 45*5/18=25/2 m/s.
Time is given t= 30 sec.
Let's find the length of the bridge,
Let the length of the bridge is X.
And whenever a train crosses the bridge then the total distance covered by the train is the length of the bridge +it's own length (train's length),
According to the motion's 1st law distance or displacement = speed *time.
X+130 =25/2*30.
2(X+130)=750.
2X+260= 750.
X= (750-260)/2= 245m.
(1)
DURAI said:
6 years ago
Well said, thanks @Coolburn.
(1)
Sonik Salam said:
5 years ago
260+2x=750.
2x=750-260,
2x=490,
And x = 490/2 = 245m.
2x=750-260,
2x=490,
And x = 490/2 = 245m.
(1)
Sid said:
5 years ago
Why it is +x, it also be -x, right?
(1)
Deepak Sahoo said:
4 years ago
Thanks for explaining the answer @Fathima.
(1)
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