Question

175 m long train crosses another train of length 100 m in 15 sec running in same direction.if the speed of first train is 90 km/hr. Then find the speed of the second train in km

Answer 1

First of all convert the speed to SI unit.

Speed of train = 72 km/h =72000 m/h

=72000 m/3600 s= 20 m/s

For the train just to cross the electric pole, it has to move through a distance equal to its length 60 m.

Explanation: Let us assume that the front part of the train is at the electric pole.

For the train to pass the pole, the rear part must move forward and just reach the pole.

It means, the train will pass its own length of 60 m to pass the pole.

Time taken to cross = distance travelled/time taken = length of the train / speed of train

= 60 m/20 m^s-1 =3 s

hope it will help u....