Question

Two trains of the same length but with different speed pass a ststic pole in 5sec and 6sec respectively .In what time will they are moving in the same direction

Answer 1

let the speeds of the trains be A and B and

their length be L

A = L/4

B = L/5

now when they move in same direction

to cross one train, the other train has to cover 2L distance

now

relative velocity = L/4 - L/5 = L/20

therefore time taken = 2L/L/20 = 40 sec