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 11 of 25.
Irene said:
8 years ago
From this formula 2 (130 + x) = 750 ,shouldn't the 2 outside multiple both 130 and x?
I believe it shd be;
160+2x =750,
2x=750-160,
2x=590/2,
x=295m,
2(130+x)=750.
I believe it shd be;
160+2x =750,
2x=750-160,
2x=590/2,
x=295m,
2(130+x)=750.
Leki said:
7 years ago
Distance= Time * speed.
1km=1000m.
1hr=3600sec.
Time=d/t.
=1000/3600=5/18.
There distance: 5/18*45=25/2.
Length=t/d*s.
130+x=25/2*30.
130+x=375.
X = 375-130 = 245.
1km=1000m.
1hr=3600sec.
Time=d/t.
=1000/3600=5/18.
There distance: 5/18*45=25/2.
Length=t/d*s.
130+x=25/2*30.
130+x=375.
X = 375-130 = 245.
TFreeN said:
9 years ago
This is very shortcut key.
Simple 45km = 45000 mitr.
1hrs = 3600 sec.
= 45000/3600.
=12.5.
12.5 * 30 second cross.
= 375.
And 375 - 130 mtr.
= 245 mtr.
Simple 45km = 45000 mitr.
1hrs = 3600 sec.
= 45000/3600.
=12.5.
12.5 * 30 second cross.
= 375.
And 375 - 130 mtr.
= 245 mtr.
Shamama Mubarak said:
1 year ago
Length of train = 130m
Length of bridge = ?
1hr = 3600sec
= 3600/30
= 120.
1km = 1000m
= 45000/120
= 375m
The length of the train is less total.
375-130 = 245.
Length of bridge = ?
1hr = 3600sec
= 3600/30
= 120.
1km = 1000m
= 45000/120
= 375m
The length of the train is less total.
375-130 = 245.
(54)
WDL said:
3 years ago
Speed = 45*(5/18)=25/2 m/s.
Displacement = speed * time(here time is 30sec).
X + 130 = 25/2 * 30.
2(X + 130) =750.
2X + 260 = 750.
X = (750-260)/2= 245m.
Displacement = speed * time(here time is 30sec).
X + 130 = 25/2 * 30.
2(X + 130) =750.
2X + 260 = 750.
X = (750-260)/2= 245m.
(12)
Mannu said:
1 decade ago
What is the significance of train's length. Since the train crossed the bridge so distance should be of the bridge only. Why that bridge and train added?
Babool said:
8 years ago
Speed = 45 * 5 m/sec = 25 m/sec.
18 2
Time = 30 sec.
Let the length of the bridge be x metres.
Then, 130 + x = 25.
30 2
2(130 + x) = 750
x = 245 m.
18 2
Time = 30 sec.
Let the length of the bridge be x metres.
Then, 130 + x = 25.
30 2
2(130 + x) = 750
x = 245 m.
Nirmala said:
1 decade ago
Why train length added with bridge length what's the logic behind it?
Why bridge length is not subtracted from train length?
Please clear my doubt.
Why bridge length is not subtracted from train length?
Please clear my doubt.
Vidya said:
10 years ago
1 hour = 60 min.
1 min = 60 sec.
1 km = 1000 m.
Km per hour to m per sec:
1 km/1 hour = 1000 m/60*60 sec.
=> 1 kmph = 1000/3600 sec = 5/18 sec.
1 min = 60 sec.
1 km = 1000 m.
Km per hour to m per sec:
1 km/1 hour = 1000 m/60*60 sec.
=> 1 kmph = 1000/3600 sec = 5/18 sec.
Jimian said:
9 months ago
Given, train length s = 130.
Let, the bridge length is x.
Total passing length = velocity * time.
S + x = vt.
130 + x = 45 * (5/18) * 30.
x = 245m.
Let, the bridge length is x.
Total passing length = velocity * time.
S + x = vt.
130 + x = 45 * (5/18) * 30.
x = 245m.
(25)
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