A passenger sitting in a train A moving at 90 km h - 1 observes another train B moving in the opposite direction for 8 s . If the velocity of the train B is 54 km h - 1 , then length of train B is:

Step-by-step solution

Let the velocity of A be v A and the velocity of B be v B . The relative velocity is v → B A   = v → B - v → A ⇒ v B A =   54 - ( - 90 ) = 144   km   h - 1 ⇒ v B A =   40   m   s - 1 Time = length v B A ⇒ length =   40   m   s - 1   ×   8   s = 320   m