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:
249 comments Page 4 of 25.
Sanilam Guha said:
5 years ago
(0.130+x) = (45 * 30)/3600.
If assume x is bridge length;
OR, 0.130 + x = 0.375.
OR, X = 0.375 - 0.130.
OR, X = 0.245 KM OR 245 M.
Am I right?
If assume x is bridge length;
OR, 0.130 + x = 0.375.
OR, X = 0.375 - 0.130.
OR, X = 0.245 KM OR 245 M.
Am I right?
(2)
Arup Kumar subudhi said:
5 years ago
Train Speed is 45 km/sec = (45*5)/18 = 25/2 m/s.
= (25*15)/(2*15) m/s,
= 375/30 m/s.
375 m in 30 sec, so bridge length is = 375 - 130 = 245m.
= (25*15)/(2*15) m/s,
= 375/30 m/s.
375 m in 30 sec, so bridge length is = 375 - 130 = 245m.
(2)
Nusrat fathima said:
2 decades ago
I have solved this problem in a different way, is this right way to solve?
speed=25/2 m/sec
length of the bridge be x m
total distance = speed * time
x + 130 = 30 * 25/2
x + 130 = 375
x = 245 m
is the above method to solve this problem right?
Please help.
speed=25/2 m/sec
length of the bridge be x m
total distance = speed * time
x + 130 = 30 * 25/2
x + 130 = 375
x = 245 m
is the above method to solve this problem right?
Please help.
(1)
Coolburn said:
2 decades ago
Hi, I had my own solustion on that
45 km/hr
1km = 1000m
1hr = 3600 sec
45 km/hr convert to metter
=45000 m
=3600 sec.
45000/3600
=12.5
Since 30 sec can cross the bridge
=12.5*30
=375-130
=245m
45 km/hr
1km = 1000m
1hr = 3600 sec
45 km/hr convert to metter
=45000 m
=3600 sec.
45000/3600
=12.5
Since 30 sec can cross the bridge
=12.5*30
=375-130
=245m
(1)
Jagabandhu patra said:
1 decade ago
(45000/3600*30)-130 = 245.
(1)
Vishali said:
1 decade ago
Hi friends I did in a different way:
Let the length of train b = 130.
Let the length of bridge b = x.
Therefore distance = x+130.
Time = 30 sec.
S = 45 km/h = 45*5/18 = 25/2 m/s.
So, in this case distance = 375 m.
So, d = x+130 substituting the value of d (distance).
We get 375-130 = x.
x = 245m.
Let the length of train b = 130.
Let the length of bridge b = x.
Therefore distance = x+130.
Time = 30 sec.
S = 45 km/h = 45*5/18 = 25/2 m/s.
So, in this case distance = 375 m.
So, d = x+130 substituting the value of d (distance).
We get 375-130 = x.
x = 245m.
(1)
Sohail Khan said:
1 decade ago
We know that:
Time = Distance/Speed.
Suppose length of the bridge is X mtr.
Length of the train is 130 mtr.
So total distance = 130+X.
30 = (130+X)/45*(5/18).
Then the value of X is 245 mtr.
Time = Distance/Speed.
Suppose length of the bridge is X mtr.
Length of the train is 130 mtr.
So total distance = 130+X.
30 = (130+X)/45*(5/18).
Then the value of X is 245 mtr.
(1)
Ramkumar gadi said:
1 decade ago
Time taken by the train to cross object which is in motion in relative motion we have formulas:
T = (a+b)/(U+V) and T = (a+b)/(U-V).
Let be b = x.
So here we have U = Speed of train; a = Length of train = 130m.
V = Speed of object; B = Length of object.
V = 0; b = x; T = 30s.
S = 45 km/h = 45*5/18 = 25/2 m/s.
30 = (130+x)/(25/2+0).
= 30+25/2 = 130+x.
x = 245m.
T = (a+b)/(U+V) and T = (a+b)/(U-V).
Let be b = x.
So here we have U = Speed of train; a = Length of train = 130m.
V = Speed of object; B = Length of object.
V = 0; b = x; T = 30s.
S = 45 km/h = 45*5/18 = 25/2 m/s.
30 = (130+x)/(25/2+0).
= 30+25/2 = 130+x.
x = 245m.
(1)
Sivakumar.s said:
1 decade ago
Train 130 meters long. Travel 45 km/hr.
To convert m/s = 25/2.
So 2 second train will move 25 meter. So 30 second means.
2*15 = 30 second.
25*15 = 375.
So train travelling 375 meters to reduce the train meters.
375-130 = 245.
So the bridge meter is 245 meters.
To convert m/s = 25/2.
So 2 second train will move 25 meter. So 30 second means.
2*15 = 30 second.
25*15 = 375.
So train travelling 375 meters to reduce the train meters.
375-130 = 245.
So the bridge meter is 245 meters.
(1)
ARYAN said:
7 years ago
Length of the train = 130m.
speed =45km/h so, 45/3.6=12.5.
12.5*time=12.5*30=375m.
length of the bridge = [375-130] = 245m ANS.
speed =45km/h so, 45/3.6=12.5.
12.5*time=12.5*30=375m.
length of the bridge = [375-130] = 245m ANS.
(1)
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