Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 8)
8.
A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
40 sec
42 sec
45 sec
48 sec
Answer: Option
Explanation:

Formula for converting from km/hr to m/s:   X km/hr = X x 5 m/s.
18

Therefore, Speed = 45 x 5 m/sec = 25 m/sec.
18 2

Total distance to be covered = (360 + 140) m = 500 m.

Formula for finding Time = Distance
Speed

Required time = 500 x 2 sec = 40 sec.
25

Discussion:
78 comments Page 4 of 8.

Gurwinder singh said:   8 years ago
Why (x*5/18) mps?

Prasad kapal said:   8 years ago
But we added 500 with 140.

Praveena said:   1 decade ago
Why should we add 360 and 140?

A train of length 360 is moving on 140 m bridge. It is not covering 360 m distance and 140 m distance. Then why should we add two lengths?

Dwaraka said:   2 decades ago
Hi rajasekaran the solution
speed=55km/hr
= (55*1000)/(60*60)
=15.27m/s

Total distance=the bridge distance+distance of the train to cross the bridge
d=470+140=610
time=d/s=610/15.27=39.94s

Rohan said:   7 years ago
Why we have to add the length of the train?

Antony said:   2 decades ago
How it should come 25/2,could you explain me as soon as possible

Rajasekaran said:   2 decades ago
A train 470 m long is running at a speed of 55 km/hr. In what time will it pass a bridge 140 m long?

pls explain it

Ramashish mallah said:   2 decades ago
Thank You.



Rahul, You explained very well and cleared all my confusing.



I am greatful to you.



Regards,

Ramashish Mallah

ramashish.mallah[at]gmail.com

Antony said:   2 decades ago
5/18 comes .because we want to express the unit of speed to m/s

1km/hr=1000m/3600s=5/18 m\s

Sreee said:   6 years ago
Please explain to me why we are adding train length and bridge length. The train is moving on the bridge only.

And they asked only the time taken to move on the bridge.

Please explain to me in detail.


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