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:
254 comments Page 11 of 26.
Ishwarya said:
8 years ago
Shouldn't we are considering from the time the train's front enters the bridge till the tail is completely off the bridge as 30 seconds?
Then it would be 375- (130+130) =115m.
Then it would be 375- (130+130) =115m.
Parthiban said:
1 decade ago
Easy to find no need to put x and y.
45000m/360seconds = 125 mps.
30 seconds so, crossing bridge.
30*125=375m.
Subtract the train meter : 130m.
Answer : 375-130=245m.
45000m/360seconds = 125 mps.
30 seconds so, crossing bridge.
30*125=375m.
Subtract the train meter : 130m.
Answer : 375-130=245m.
Vinod choudhary said:
10 years ago
Speed = (length of bridge + length of train) /time = (L + l) /t.
45 x (5/18) = (L + 130) /30,
45 x 30 x (5/18) = (L + 130) ,
375 = L + 130,
L = 375 - 130,
L = 245 m.
45 x (5/18) = (L + 130) /30,
45 x 30 x (5/18) = (L + 130) ,
375 = L + 130,
L = 375 - 130,
L = 245 m.
P.Deepika said:
1 decade ago
I Had one doubt.,
Crossing means we want to consider as opposite direction as formula (u-v) as (375-130) = 245?
Is This Write Or Wrong, If Any One Please Answer Me.
Crossing means we want to consider as opposite direction as formula (u-v) as (375-130) = 245?
Is This Write Or Wrong, If Any One Please Answer Me.
Irene said:
9 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:
8 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:
10 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:
2 years 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.
(57)
WDL said:
4 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:
2 decades 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?
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