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 5 of 25.
Banda said:
7 years ago
Hi, Good explanation. Thanks all.
(1)
Ahmad said:
7 years ago
(130 + x)/30 = 25/2.
What is meant by this?
What is meant by this?
(1)
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)
Sonik Salam said:
5 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)
Uvitha said:
2 decades ago
Can you explain me in detail ?
Nusrat fathima said:
2 decades ago
Hi Uvitha,
Speed=25/2 m/sec
then we find the lenght of the bridge using the formula
distance/time = speed
where distance = length of train + x
Time = 30 sec & speed = 25/2
=> 245 m
Speed=25/2 m/sec
then we find the lenght of the bridge using the formula
distance/time = speed
where distance = length of train + x
Time = 30 sec & speed = 25/2
130 + x 25
------- = --
30 2
=> 245 m
Sai said:
2 decades ago
Hi all, i've solved this problem in anotha way
given,
time=30 sec and speed=45km i.e 45x5/18
so im finding the distance= time x speed = 30 x 225/18 = 375m
thus,the distance travelled by the train is 375m and the length given was 130m
so 375-130 = 245m
Now my question is..could someone insist me that the method followed by me is the right one?
given,
time=30 sec and speed=45km i.e 45x5/18
so im finding the distance= time x speed = 30 x 225/18 = 375m
thus,the distance travelled by the train is 375m and the length given was 130m
so 375-130 = 245m
Now my question is..could someone insist me that the method followed by me is the right one?
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