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:
245 comments Page 3 of 25.
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?
Rajesh said:
1 decade ago
Hi friends, for most of these questions, just understanding the questions is enough and you don't need any formulas.
In the above problem train passes at 45 km/hr so for 1s it will go (45*5/18) = 12.5 m.
And for 30 s it will go 12. 5 * 30 = 375 m.
But we have to reduce trains length (for crossing a pole or person or bridge). So 375-130 = 245 m.
In the above problem train passes at 45 km/hr so for 1s it will go (45*5/18) = 12.5 m.
And for 30 s it will go 12. 5 * 30 = 375 m.
But we have to reduce trains length (for crossing a pole or person or bridge). So 375-130 = 245 m.
Anusha said:
9 years ago
Here, the formula is:
Time is taken to cross the bridge = length of the bridge + length of the train/speed of the train.
To convert km to m we have to multiply with = (5/18).
Converting km to m:
45 * 5/18 = 25/2.
Assume length of the bridge be x then,
30 = (x + 130)/(25/2),
So by calculating we get the x value i.e length of the bridge.
Time is taken to cross the bridge = length of the bridge + length of the train/speed of the train.
To convert km to m we have to multiply with = (5/18).
Converting km to m:
45 * 5/18 = 25/2.
Assume length of the bridge be x then,
30 = (x + 130)/(25/2),
So by calculating we get the x value i.e length of the bridge.
Peter said:
9 years ago
I think it would be better if we say the train is running by 45 KM/HR so let's take it in details KM/HR = 1000 M/3600 S so = 10 /36 = 5 /18.
So, train is running by 45 KM/HR = 45 * (5/18) = 12.5 M/S.
Crossed bridge in 30 S so 12.5 * 30 = 375 minus it's from train length so 375 - 130 = 245 M the length of the bridge.
Wish to be easier.
So, train is running by 45 KM/HR = 45 * (5/18) = 12.5 M/S.
Crossed bridge in 30 S so 12.5 * 30 = 375 minus it's from train length so 375 - 130 = 245 M the length of the bridge.
Wish to be easier.
Muzammil said:
1 year ago
Length of train 130, speed 45 km/hr it crosses the bridge in 30 seconds.
What is the length of the bridge?
45km = 45000 m
1hr = 3600 s.
So
45000/3600 = 12.5 m/s
the train crosses a bridge in 30 sec then
12.5 * 30 = 375
The train travelled 375 in 30 sec.
Then distance - train length = bridge length.
375 - 130 =245.
bridge length = 245.
What is the length of the bridge?
45km = 45000 m
1hr = 3600 s.
So
45000/3600 = 12.5 m/s
the train crosses a bridge in 30 sec then
12.5 * 30 = 375
The train travelled 375 in 30 sec.
Then distance - train length = bridge length.
375 - 130 =245.
bridge length = 245.
(93)
Rohit said:
1 decade ago
< (end-point) train (start-point) >EntreR-----[BRIDGE]---< (end point) trian (start-point) >. When train end point meets bridge end point, according to this time is given 30 sec. So we have to add bridge length + train's length as total distance travelled in 30 sec. Two different way are given to solve this prblm.
Murali said:
1 decade ago
@Mannu.
Here we know only length of the train. We have to find the length of the bridge. We know the formula"s=d/t".
Here distance is "L1+L2".
Therefore "s= (L1+L2) /t".
Now we will get the answer.
By adding two distance only we will find the one distance (if you know the one distance then find the length of the train).
Here we know only length of the train. We have to find the length of the bridge. We know the formula"s=d/t".
Here distance is "L1+L2".
Therefore "s= (L1+L2) /t".
Now we will get the answer.
By adding two distance only we will find the one distance (if you know the one distance then find the length of the train).
Shah Sonu said:
2 years ago
Given TD = 130m, speed = 45km/h, Time = 30sec.
And Length of the Station = x.
speed = 45*5/18 .
=225/18.
So, the speed =25/2.
know the length of the station,
x + TD = speed * Time
x + 130 = 25/2 * 30
x + 130 = 12.5 * 30
x + 130 = 375.
x = 375 - 130,
Final x = 245.
The correct answer is option C.
And Length of the Station = x.
speed = 45*5/18 .
=225/18.
So, the speed =25/2.
know the length of the station,
x + TD = speed * Time
x + 130 = 25/2 * 30
x + 130 = 12.5 * 30
x + 130 = 375.
x = 375 - 130,
Final x = 245.
The correct answer is option C.
(28)
Anusha 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 = 245 m.
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 = 245 m.
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)
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