Problems on Trains

Important Formulas - Problems on Trains
km/hr =5/18
m/s=18/5
x km/hr = x×5/18 m/s

y m/s = y×18/5 km/hr

Speed = distance/time
s = d/t


velocity = displacement/time
v = d/t


Time taken by a train x meters long to pass a pole or standing man or a post
= Time taken by the train to travel x meters.


Time taken by a train x meters long to pass an object of length y meters

= Time taken by the train to travel (x + y) metres.


Suppose two trains or two objects are moving in the same direction at v1 m/s and v2 m/s where v1 > v2,

then their relative speed = (v1 – v2) m/s


Suppose two trains or two objects are moving in opposite directions at v1 m/s and v2 m/s ,

then their relative speed = (v1+ v2) m/s


Assume two trains of length x metres and y metres are moving in opposite directions at v1 m/s and v2 m/s, Then

The time taken by the trains to cross each other = (x+y) / (v1+v2) seconds


Assume two trains of length x metres and y metres are moving in the same direction at at v1 m/s and v2 m/s where v1 > v2, Then

The time taken by the faster train to cross the slower train = (x+y) / (v1-v2) seconds


Assume that two trains (objects) start from two points P and Q towards each other at the same time and after crossing they take p and q seconds to reach Q and P respectively. Then,


A's speed : B's speed = qv : pv