Train A running at 72 km/h overtakes Train B (length 200 m) in 36 seconds. If Train A is 300 m long, find Train B’s speed.
Show answer & explanation
Correct answer: A
Explanation
Given:
Speed of train A = 72 km/h
Length of train A = 300 m
Length of train B = 200 m
Time to cross = 36 s
Speed of train A = 72 × 5/18 = 20 m/s
Total distance = 300 + 200 = 500 m
Relative speed = 500 ÷ 36 = 13.89 m/s
Since train A is crossing train B,
20 − B = 13.89
B = 20 − 13.89
B = 6.11 m/s
Speed in km/h = 6.11 × 18/5 = 22 km/h