Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 26)
26.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
23 m
23 2 m
9
27 7 m
9
29 m
Answer: Option
Explanation:

Relative speed = (40 - 20) km/hr = ( 20 x 5 ( m/sec = ( 50 ( m/sec.
18 9

Therefore Length of faster train = ( 50 x 5 ( m = 250 m = 27 7 m.
9 9 9

Discussion:
72 comments Page 2 of 8.

Qasim said:   1 decade ago
Thanks ram. That one is really good example.

Sadik ali said:   1 decade ago
How can we find speed of slower train?

Shweta said:   1 decade ago
Can anyone tell me when we have to add relative speed and when we have to subtract?

Sindhu said:   1 decade ago
If the two trains are moving in the same direction their relative speeds are subtracted.

Raja.k said:   1 decade ago
@Swetha.

According to this question two trains are in same starting points only but the speed of the two trains is varying. So, anyway we subtract this. Did you understand now.

Wangchuk said:   1 decade ago
According to formula relative speed is added when two train are moving in opposite direction and is subtracted in same direction.

Suman CKP said:   1 decade ago
And Suppose someone ask the speed of slower train then what will be do? Not clear?

Mj pala said:   1 decade ago
If the question is to find the length of the slower train, then?

Gaurav said:   1 decade ago
As the man is sitting in the train, he has the same speed as of train, so it simply means that the faster train crosses the slower train in 5 seconds.

Harpreet said:   1 decade ago
What would be the length of slower train?


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