Aptitude - Problems on Trains - Discussion

T = D/S .

D = 2 KM = 2000M.

S = 150KM/HR = 150X5/18 = 125/3.

T = 2000/[125/3] = 2000X3/125 = 48 sec.

Generally a+b\u-v formula is used to calculate the time taken by faster train to cross the slower train but in the question it is given that slower train to cross the faster train in this condition also we can use the same formula to find the answer can anyone explain me please.

It is the formula for,

The time taken by the trains to cross each other.

It is not as, faster cross the slower or slower cross the faster.

So we use this formula here also.

Answer in 2 step.

1. a+b/u+v : as both train in opposite direction

2. Answer*3600 : to convert it into sec.

Don't worry about it.

Use simple idea of relative speed and distance.

S = U*T.

Where S = Relative distance.
U = Relative Speed of train.
T = Time taken by train.

Note:

1. If one train is crossing bridge/platform then take relative distance as "sum of length of train and bridge/platform".
2. If both are in same direction then subtracts the speeds.
3. If both are in opposite direction then add the speeds.
4. If one Train is crossing "man" then his speed is "Zero".

Please explain me how can we find 125/3?

When two train moving in opposite direction then how it possible they cross each other?

They are starting at two different points and moving in opposite direction. They are not starting at the same point.

Friend take a live example to make it understand when your going towards your home on the left side of the road and one of your friend returning from your home on your right side of the same road.

Definitely you will cross each other like this 2 train traveling in opposite direction they can cross each other.

For what purpose we are converting the kilometer into meter? can't we solve this problem with length 2km.

No need to convert Km to m, conversion is due to hr to sec because answer is in sec.