Question

A train crosses an electric pole in 5 seconds and a railway bridge of 600 m long in 35 seconds. Find the speed of the train in km/h and length of the train. ​

Answer 1

Answer: 0.1

now the second case is the railway bridge, unlike the electric pole,railway bridge is 600m long, so here, we take the starting time as when the front part of the train just starts crossing the railway bridge, so that means the rear part has to cover a distance equal to the length of the railway bridge+length of the train, for the entire train to cross the railway bridge.

so that means 600+length of the train=velocity of the train×35(equation 2)

substituting equation 1 in equation 2

let us take the velocity of the train to be v for simplicity.

we get 600+5v=35v⇒v=20m/s=20×18/5 km/h= 72km/h

so length of the train=5v=5×20=100m=0.1km