Question

Heya...
A train 300 m long is travelling at 85km/h. Find the time taken by it:
a) to cross a signal.
b) to go past the platform 500 m long.

Answer 1

(a). Time taken to cross a signal

Distance = 300m

Speed = 85km/h = 23.6m/s

t = distance÷speed

t = 300/23.6

t = 12.7s

(b). Total distance = Length of platform + length of train

Distance = 500+300 = 800m

Speed = 23.6m/s

t = 800/23.6

t = 33.8s

Answer 2

Given,

Lenght of a train = 300 m

Speed of the train = 85 Km/hr

To find,

a) The time taken by the train to cross a signal

b) The time taken by the train to go past the platform 500 m long

Solution,

We can simply solve this numerical problem by using the following process:

Mathematically,

Speed (s) = distance traveled (d)/time of journey(t)

=> Time taken(t) = speed (s)/distance traveled (d)

Now, according to the question;

While crossing a signal,

Total distance covered = length of the train = 300 m = 0.3 Km

Speed of the train

= 85 Km/hr

So, the time taken by the train to cross a signal

= speed (s)/distance traveled (d)

= (0.3 Km)/(85 Km/hr)

= 0.0035 hr = (0.0035×3600) seconds

{Since 1 hr = 3600 seconds}

= 12.7 seconds

Now, while crossing a platform 500 m long,

Total distance covered

= length of the train + length of the platform = 300 m + 500 m = 800 m = 0.8 Km

Speed of the train

= 85 Km/hr

So, the time taken by the train to cross a signal

= speed (s)/distance traveled (d)

= (0.8 Km)/(85 Km/hr)

= 0.0094 hr = (0.0094×3600) seconds

{Since 1 hr = 3600 seconds}

= 33.9 seconds

Hence, the time taken by the train to cross a signal is equal to 12.7 seconds and the time taken by the train to go past the platform 500 m long is equal to 33.9 seconds, respectively.