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 8 of 25.
Monika said:
1 decade ago
You can do this without any variable:
45 km/hr*5/18 = 25/2 m/s.
Total distance = 25/2*30 = 375.
Length of bridge = 375-130 = 245m.
45 km/hr*5/18 = 25/2 m/s.
Total distance = 25/2*30 = 375.
Length of bridge = 375-130 = 245m.
Rohit said:
1 decade ago
Please help me,
When the train crosses the bridge, shouldn't we consider the length of the train after the bridge also.
All above solutions are only by considering the start point of the train.
And if only that is considered then what is the use of the length of the train.
When the train crosses the bridge, shouldn't we consider the length of the train after the bridge also.
All above solutions are only by considering the start point of the train.
And if only that is considered then what is the use of the length of the train.
Ananth G said:
1 decade ago
@Rohit,
Length=(speed*time).
What you know take left side others stay right side, listen down.
Length
------- = speed {(130+X)/30=25/2,
Time
Than you workout cross multiply method then you get 245m.
Length=(speed*time).
What you know take left side others stay right side, listen down.
Length
------- = speed {(130+X)/30=25/2,
Time
Than you workout cross multiply method then you get 245m.
Dileep kumar said:
1 decade ago
Distance = speed/time;
Let us bridge length = x say, train travelling distance = 130 m.
The total distance is = x+130;
Speed = 25/2;time = 30sec;
:: x+130 = (25/2) 30;
x = 375-130;
= 245.
Let us bridge length = x say, train travelling distance = 130 m.
The total distance is = x+130;
Speed = 25/2;time = 30sec;
:: x+130 = (25/2) 30;
x = 375-130;
= 245.
Sunil Kumar said:
1 decade ago
Let bridge length x m then.
Length of train = 130.
Speed 45*5/18 = 12.5.
Distance=12.5*30 = 375.0-130 = 245.
Length of train = 130.
Speed 45*5/18 = 12.5.
Distance=12.5*30 = 375.0-130 = 245.
Sanjay said:
1 decade ago
B.L. = Bridge Length.
For crossing the bridge distance should be 130+ (B.L) +130.
Then why you are taking 130 + B.L?
For crossing the bridge distance should be 130+ (B.L) +130.
Then why you are taking 130 + B.L?
Thamilarasan said:
1 decade ago
Have any common formulas for easily learning?
Dumpati Mahesh said:
1 decade ago
Here we should consider as per the problem that, Train is passing only one time through the bridge. So 130+B.L. Only sanjay.
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.
Dileep kumar said:
1 decade ago
Hai friends don't be confuse with considering different formulas, let use single formula to solve these all type of questions, i.e.
Distance = speed*time; OR (D = ST) ;
Let us consider bridge length = x;
Total length (x+130) = (25/2) *30;
x + 130 = 375;
x = 375-130;
x = 245.
Distance = speed*time; OR (D = ST) ;
Let us consider bridge length = x;
Total length (x+130) = (25/2) *30;
x + 130 = 375;
x = 375-130;
x = 245.
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