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?
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 1 of 8.
Keanu said:
6 months ago
Nice answer. Thanks all.
(2)
Samama Javaid said:
7 months ago
Speed of train = v = 45km/h = 45 × 1000/3600 = 25/2 m/s,
Length of Train= S¹= 360m,
Length of Bridge=S²= 140 m,
Time taken = t1= ?
Time taken = t2=?
Solution :
t1 = S¹/v = 360×2/25 = 28.8 s.
t2 = S2/v = 140 × 2/25= 11.2 s.
Total time taken = t1 + t2= 28.8 + 11.2.
t= 40s.
Length of Train= S¹= 360m,
Length of Bridge=S²= 140 m,
Time taken = t1= ?
Time taken = t2=?
Solution :
t1 = S¹/v = 360×2/25 = 28.8 s.
t2 = S2/v = 140 × 2/25= 11.2 s.
Total time taken = t1 + t2= 28.8 + 11.2.
t= 40s.
(2)
Paschal said:
1 year ago
For a train to cover any distance, I believe it must first cover(move) its length, that is why we have to add the train length (distance) and that bridge which is static which also the train has to cover.
Correct me If I am wrong.
Correct me If I am wrong.
(7)
Dasari Monica Lucy said:
1 year ago
Given:
Distance of train = 360m,
Speen = 45km/hr,
Distance of bridge = 140m,
45×5/18=12.5
360+140=500
T=D/S =500/12.5.
T= 40.
Distance of train = 360m,
Speen = 45km/hr,
Distance of bridge = 140m,
45×5/18=12.5
360+140=500
T=D/S =500/12.5.
T= 40.
(17)
Disha patel said:
2 years ago
How 25/2? Please explain.
(15)
Anushiya said:
2 years ago
Aakriti.
Suppose I take the length as 140 only then what happened? Please explain me.
Suppose I take the length as 140 only then what happened? Please explain me.
(5)
Aakriti said:
4 years ago
@Sreee,
According to question, the train should cross the bridge ie. 360m long train should cross 140m long bridge.
Hence, we should add 360 and 140 for total length.
According to question, the train should cross the bridge ie. 360m long train should cross 140m long bridge.
Hence, we should add 360 and 140 for total length.
(6)
Sreee said:
4 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.
And they asked only the time taken to move on the bridge.
Please explain to me in detail.
Dheeraj said:
5 years ago
Here length of train =360m.
Length of bridge =140m.
Speed of train =45km/h.
To convert into m/s multiplying it with 5/18.
Now to find time=Distance/speed.
Distance=length of both train and bridge.
Distance=140+360.
Speed=45*5/18=25/2.
Time=500/25/2=500*2/25=40.
Length of bridge =140m.
Speed of train =45km/h.
To convert into m/s multiplying it with 5/18.
Now to find time=Distance/speed.
Distance=length of both train and bridge.
Distance=140+360.
Speed=45*5/18=25/2.
Time=500/25/2=500*2/25=40.
(7)
Madhav Kulkarni said:
5 years ago
Train Length=360 Speed=45km/h=45*(5/18)=12.15m/s.
So Train Speed is 12.15m/s.
Bridge Length = 140.
Speed = Distance/Time.
12.15 = 360+140/time.
Time = 360+140/12.15.
= 500/12.5.
= 40.
So, the Time Require to cross 140m Bridge is 40sec.
So Train Speed is 12.15m/s.
Bridge Length = 140.
Speed = Distance/Time.
12.15 = 360+140/time.
Time = 360+140/12.15.
= 500/12.5.
= 40.
So, the Time Require to cross 140m Bridge is 40sec.
(5)
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