Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 6)
6.
A train 240 m long passes a pole in 24 seconds. How long will it take to pass a platform 650 m long?
Answer: Option
Explanation:
| Speed = |  |
240 |  m/sec = 10 m/sec. |
| 24 |
 Required time = |
|
240 + 650 | sec = 89 sec. |
| 10 |
Discussion:
202 comments Page 3 of 21.
Neetu said:
1 decade ago
We are adding 240 and 650 because the train needs to cross the entire platform. CROSSING means the last coach should cross the end of the platform. That's why we are adding both lenghts.
Kiran,
We cannot solve in your way because a train will never take the same time in crossing a pole and a platform. The train crossing the pole and crossing the platform is not same.
Kiran,
We cannot solve in your way because a train will never take the same time in crossing a pole and a platform. The train crossing the pole and crossing the platform is not same.
Vinay Kumar said:
5 years ago
Here 240 is added to the length 650 because it's the length of the train in the question they given the pole is crossed in 24 seconds because we can find the length of the train using the time taken to cross the pole(where the pole length is negligible) so to calculate the time required is;
240(length of the train) + 650(length of the platform) = 890m,
890/10 = 89s.
240(length of the train) + 650(length of the platform) = 890m,
890/10 = 89s.
Vipul said:
1 decade ago
Whoever thinks it is 65m, take a look.
length of platform is 650 m long, and length of train is 240m.
Train can't cross the platform by just travelling 650m, it has to travel 240m more so that its last bogie crosses the platform.
Therefore train has to travel total distance 650+240=890m to cross the platform.
And its speed is 10m/s, therefor it will take 89 sec.
length of platform is 650 m long, and length of train is 240m.
Train can't cross the platform by just travelling 650m, it has to travel 240m more so that its last bogie crosses the platform.
Therefore train has to travel total distance 650+240=890m to cross the platform.
And its speed is 10m/s, therefor it will take 89 sec.
Sudarsan said:
1 decade ago
Given train distance is = 240 m.
Platform distance = 650 m.
Speed of train = 240/24= 10 m/s.
Let the platform be AB = 650 m.
And train length be CD = 240 m.
The time taken is 65 s for D of the train (the front part).
Thus for the train to completely pass i.e. C to pass the total distance is (240 + 650 m).
Thus time taken for the train to pass is 89 s.
Platform distance = 650 m.
Speed of train = 240/24= 10 m/s.
Let the platform be AB = 650 m.
And train length be CD = 240 m.
The time taken is 65 s for D of the train (the front part).
Thus for the train to completely pass i.e. C to pass the total distance is (240 + 650 m).
Thus time taken for the train to pass is 89 s.
The Guide said:
1 decade ago
For problems on trains for most of the problems we use one formulae
time=(l1+l2)/s1+s2
for eg in the above problem
given length of train 240m and time 24 sec then speed=10m/sec
given length of platform 650
their is no speed s2 because platform is a stationary object
so substitue all the values in above formulae
we get time t=(240+650)/10= 89sec
time=(l1+l2)/s1+s2
for eg in the above problem
given length of train 240m and time 24 sec then speed=10m/sec
given length of platform 650
their is no speed s2 because platform is a stationary object
so substitue all the values in above formulae
we get time t=(240+650)/10= 89sec
Milesh bhange said:
9 years ago
Don't forget to add trains length, question is asking answer about how much time it will take to cross a platform means train will star platforms one end to another in 65 seconds and what about trains end means its length 240 meter question said how much time it will take to cross a whole train means trains end. You have to add 240 its trains length.
Saji said:
2 decades ago
There is no need of adding 240 and 650..because the question is to calculte the time taken by train to cross the bridge...
so after finding the speed of the train v can calculate directly the time taken by the train by
time=dis/speed
time=650/10
time=65 sec
this may be correct..please suggest me an exact reason why we are adding 650 to 240
so after finding the speed of the train v can calculate directly the time taken by the train by
time=dis/speed
time=650/10
time=65 sec
this may be correct..please suggest me an exact reason why we are adding 650 to 240
Rajiv sd said:
8 years ago
Here pole consider as a point of reference, but platform not a point if consider engine only cross the platform from starting of platform to end (i.e also consider as crossed) 65 sec is correct, but if consider entire train (engine to the last van) cross the platform end to end length of the platform should be added hence 89sec is correct.
Leela venkateswara aro said:
1 decade ago
Let length of the train=l=240m.
Time taken to cross platform=t=?
Platform length=a=650m.
Speed of the train=S= (length of the train+length of platform)/time taken to cross platform.
s = (240+650) /t.
s =240/24=10m/s.
10 = 890/t.
T = 890/10 = 89sec.
During this time the train has to cross its own length as well as platform length.
Time taken to cross platform=t=?
Platform length=a=650m.
Speed of the train=S= (length of the train+length of platform)/time taken to cross platform.
s = (240+650) /t.
s =240/24=10m/s.
10 = 890/t.
T = 890/10 = 89sec.
During this time the train has to cross its own length as well as platform length.
Nagesh Shirsat said:
1 decade ago
Well the question is how long train take to cross the platform, in order to do so, train has to cover total length of platform i.e. 650 m and its own length i.e. 240 m, hence 240+650/10=89. 65 is when the engine crosses the platform, it has got to travel train length too to cross the platform entirely. I hope all doubts are clear now.
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