Question

Heya ✌️
Answer dis....​

Answer 1

Given lengths of each train L = 200 m..

let us assume the velocities of each train be V₁ & V₂ respectively.

(i) Given one over takes the other in 20 sec.

   ⇒ when both the trains are moving in same direction on train over takes in 20 sec.

   so the train has to travel a distance of (200 + 200) = 400 m.

(∵ it has to cover length of its self and length of the other train)

  since both the trains are moving in same direction their relative speed becomes, (V₁ -V₂).

so, distance =  relative speed x time taken

   ⇒ 400 m = (V₁ -V₂) x 20

   ⇒ V₁ -V₂ = 400/20 = 20 m/s --------(1)

(ii) Also given it takes 10 seconds to cross the other.

⇒ When the trains are moving opposite to each other time taken to cross = 10 sec

here also the train has to cover the distance of (200+200) = 400 m.

Now since both are moving in opposite directions their relative speeds = (V₁ +V₂).

so, 400 = (V₁ +V₂) x 10

⇒ V₁ +V₂ = 40 m/s   -------(2)

Now solving equations (1) & (2) we get

    V₁ = 30 m/s ; V₂ = 10 m/s.

HOPE THIS HELPS YOU !!    : )