Question

2 2. One train A 100 m long is moving in a direction with a speed of 20 m/s. Another train B 150 m long is moving with a speed of 30 m/s in the opposite direction. The train B crosses the train A in a time A) 5 s B) 10 s C) 18 s D) None of these a​

Answer 1

Given:

Length of first train = Sa = 100m

Speed of first train = Va = 20m/s

Length of second train = Sb = 150m

Speed of first train = Vb = 30m/s

To Find:

The time when train B crosses train A

Solution:

Velocity of approach = Va + Vb

= 20 + 30

= 50m/s

Distance covered by train = Sa + Sb

= 150 + 100

= 250m

Time = t = S/V

= 250/50

= 5

Answer: The time when train B crosses train A is 5 seconds