1. Two trains each of length 150 m are mov
opposite direction at 36 km/hr and 72
respectively. Time taken by them to just
each other completely is
(1) 4 s
(2) 6 s
(3) 8 s
(4) 10 s
QUALITY ANSWER NEEDED⚡☠️
Answers
( OPTION D )
GiveN:
Two trains of equal lengths are crossing each other in opposite direction.
Their speeds are 36 km/hr and 72 km/hr
To FinD:
Time taken to cross each other?
Step-by-Step Explanation:
When two train passes a moving object (having some length) in the opposite direction, they have to cover the sum of their lengths.
Hence,
⇒ Distance to be covered = 150 m × 2
⇒ Distance to be covered = 300 m
Their speeds are opposite to each other. Hence, the relative speed will be their sum.
Unit conversion first:
36 km/hr = 36 × 5/18 m/s = 10 m/s
72 km/hr = 72 × 5/18 m/s = 20 m/s
Relative speed:
= 10 m/s - (-20 m/s)
= 10 m/s + 20 m/s (Their sum)
= 30 m/s
Then,
Time taken by the two trains to cross each other = Sum of length of trains / Relative speed of trains
⇒ Time taken = 300 m / 30 m/s
⇒ Time taken = 10 s
Therefore,
The two trains crossed each other in 10 seconds.