In a circular race of 5000 m, starting from the same point, the speeds of two contestants A and B are 36 km/h and 54 km/h, respectively. What is the difference between the time taken (in seconds) to meet for the first time when they are running in opposite directions and when they are running in the same direction?
Show answer & explanation
Correct answer: B
Explanation
The Correct answer is option 2 i.e. 800
Given that
The speeds of contestants A and B are 36 km/h and 54 km/h, respectively.
The distance of a circular track is 5000 m
⇒ the relative speed of A and B when they travel in the same direction = 54 - 36 = 18 km/h = 5 m/s
⇒ the relative speed of A and B when they travel in opposite directions = 54 + 36 = 90 km/h = 25 m/s
⇒ The time taken (in seconds) to meet for the first time when they are running in opposite directions = 5000/25 = 200 seconds
Similarly,
⇒ The time taken (in seconds) to meet for the first time when they are running in the same directions = 5000/5 = 1000 seconds
Hence, the required difference is 1000 - 200 = 800 seconds.