Aptitude - Problems on Trains - Discussion

We add both the length of the train and platform because the train has to cross also its tail from the platform. If, the only head of train (engine) crosses the platform its other parts remain on the platform.

Train Length 240m long.
Time to pass pole = 24 second.

Speed= 240/24=10 m/s.

For length 650 m = 240+650=890m.
Speed = 890/10=89.

650/(240/24) = 65.

I get confuse. What is the correct answer?

Speed=(lt+lp)/time.
lt = length of the train.
lp = lenght of the platform.

Without adding platform length the train speed?
Seed=(240)/24.
Speed=24m/s.
with platform length.
Time=(240+650)/10.
Time=89sec.

Can we add 650+240+240? Because the train crosses between the two ends of the platform.

@All.

Why we take (240+ 65)?
I think 240/24 =10m/sec,
Platform length= 650,
Time= 650/10 = 65.

@Nithu.

When the train passes from the platform then the length of the train from start to end will pass the platform at the specific speed. So the train length will be added with a platform.

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.

The train 240 metres long, passes a stationary point in 24 seconds.

It passes the distance its own length of 240 metres in 24 seconds.

So, it passes 240 metres in 24 seconds.
Its speed is = 240 metres in 24 seconds.
=240 / 24 = 10 metres /second.

To pass a platform of length 650 metres, it should pass the platform and its own length of 240 metres, (to clear the platform),.

So, it should pass 650+240 = 890 metres.

At a speed of 10 metres per second, it will cross 890 metres in 89 seconds.