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 22 of 25.
Kavya said:
6 years ago
D= S * T.
D = 45 * 5/18 * 30 = 375m,
375-130=245m.
D = 45 * 5/18 * 30 = 375m,
375-130=245m.
(2)
Mahamud said:
5 years ago
Can you explain, How come25/2?
Kaushik vinay said:
5 years ago
45*18/5 = 25/3.
Priyanka Priyadarshini Samal said:
5 years ago
We have to calculate speed.
Speed = 45*5/18=25/2 m/s.
Time is given t= 30 sec.
Let's find the length of the bridge,
Let the length of the bridge is X.
And whenever a train crosses the bridge then the total distance covered by the train is the length of the bridge +it's own length (train's length),
According to the motion's 1st law distance or displacement = speed *time.
X+130 =25/2*30.
2(X+130)=750.
2X+260= 750.
X= (750-260)/2= 245m.
Speed = 45*5/18=25/2 m/s.
Time is given t= 30 sec.
Let's find the length of the bridge,
Let the length of the bridge is X.
And whenever a train crosses the bridge then the total distance covered by the train is the length of the bridge +it's own length (train's length),
According to the motion's 1st law distance or displacement = speed *time.
X+130 =25/2*30.
2(X+130)=750.
2X+260= 750.
X= (750-260)/2= 245m.
(1)
DURAI said:
5 years ago
Well said, thanks @Coolburn.
(1)
Sanilam Guha said:
4 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:
4 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)
Sonik Salam said:
4 years ago
260+2x=750.
2x=750-260,
2x=490,
And x = 490/2 = 245m.
2x=750-260,
2x=490,
And x = 490/2 = 245m.
(1)
Sid said:
4 years ago
Why it is +x, it also be -x, right?
(1)
Deepak Sahoo said:
4 years ago
Thanks for explaining the answer @Fathima.
(1)
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