Question

A 200 m long train travelling at 72 kmph
crosses a platform in 20 seconds. Find
the length of the platform.

▪︎300 meters
▪︎250 meters
▪︎None of these
▪︎200 meters​

Answer 1

Given:

Length of train = 200m

Speed of train = 72km/hr = 20m/s

To Find:

The Length of the platform.

Solution:

• The total distance travelled by the train for it to cross the platform is
• Distance = Length of platform + Length of train

Let Length of platform = L

Then,

• Total distance travelled by train = L + 200m
• Distance = speed x time
• Distance = 20 x 20 = 400m = L + 200m.

Therefore the length of the platform is 200m

Answer 2

Given:

(i) A 200 m long train travelling at 72 kmph  crosses a platform in 20 seconds.

To find:

(i) The length of the platform.

Solution:

First of all let us find the speed of the train in m/s.

Speed(S) = 72 kmph.

= (72*1000)/3600 m/s

= 20m/s

Distance travelled in 20s

= (20*20)m

= 400m

Length of the platform = Distance travelled in 20s - Length of the train

= (400-200)m

= 200m

So, the length of platform is 200m