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 13 of 25.
Reethu said:
10 years ago
Hi,
Can anyone explain what is 5/18 here? I couldn't get this.
Can anyone explain what is 5/18 here? I couldn't get this.
Amar said:
10 years ago
Train length bridge length train length.
Logically we should add train twice the train length, since crossing the bridge means train is not yet on the bridge and then it should be rolled off from bridge?
i.e , (x+2*130)/30 = 55 km/hr.
What say?
Logically we should add train twice the train length, since crossing the bridge means train is not yet on the bridge and then it should be rolled off from bridge?
i.e , (x+2*130)/30 = 55 km/hr.
What say?
Shekar v said:
10 years ago
45000 meters/3600 seconds = 12.5.
12.5*30 sec = 375.
375-130 = 245.
12.5*30 sec = 375.
375-130 = 245.
Sonu said:
10 years ago
Hi,
Could you please advise why we added x to the distance covered?
Could you please advise why we added x to the distance covered?
Sharmin said:
10 years ago
30 = 130+x/45*3.6 = 245.
Swamy said:
10 years ago
Well,
36 sec --- 450 mt.
30 sec --- 375 mt.
Then, 375-135 = 275 mt.
36 sec --- 450 mt.
30 sec --- 375 mt.
Then, 375-135 = 275 mt.
K.vaishnavi said:
1 decade ago
Yes the simple method is:
Solution: Let length of the train = 130 m.
T = 30 s.
S = 45 km/hr.
= 45(5/18) m/s.
=12.5 m/s.
Distance = 12.5.
= 12.5*30 = 375.
Therefore the length of the bridge = 375-130 = 245 m.
Solution: Let length of the train = 130 m.
T = 30 s.
S = 45 km/hr.
= 45(5/18) m/s.
=12.5 m/s.
Distance = 12.5.
= 12.5*30 = 375.
Therefore the length of the bridge = 375-130 = 245 m.
Santosh said:
1 decade ago
Why we are subtracting the length of bridge?
Ayaz husain said:
1 decade ago
The role of 30 sec is, the first wheel of the train enters the bridge and the last wheel of the train leaves the other end point of the bridge in 30 sec. So the train has to train the bridge length plus the length of its own to cross the bridge.
Poonam Pipaliya said:
1 decade ago
What is role of 30 sec and from where it comes?
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