Question

A train is running at a speed of 72 km/h. It crosses a bridge of length half kilometer in 1 minute. Calculate the length of the train

Answer 1

Let the length of train is x m.

speed of train, v = 72 km/h

= 72 × (1000m)/(3600 s)

= 72 × 5/18 m/s

= 20 m/s

hence, speed of train in m/s is 20m/s

now, length of bridge, L = 0.5 km = 0.5 × 1000m = 500m

time taken by train to cross the bridge , t = 1min = 60 sec .

now apply , t = (x + L)/v

so, 60 = (x + 500)/20

or, 60 × 20 = (x + 500)

or, 1200 = x + 500

or, x = 700

hence, length of train is 700m

Answer 2

Answer:

let the length of the train be x.

speed- 72 km/hr = 72x5/18 = 20 m/s

then we will find the length of rain