In a circular race of 840 m, A and B start running in the same direction at…
2024
In a circular race of 840 m, A and B start running in the same direction at the same time from the same point at the speeds of6 m/s and 12 m/s, respectively. After how much time will they meet next?
- A.
140 s
- B.
20 s
- C.
40 s
- D.
70 s
Attempted by 4 students.
Show answer & explanation
Correct answer: A
Understand the Concept:
When two runners start from the same point and move in the same direction, the faster runner meets the slower runner again when the faster runner has covered exactly one full lap more than the slower runner.
Calculate Relative Speed:
Speed of A = 6 m/s
Speed of B = 12 m/s
Relative speed = Speed of B - Speed of A = 12 m/s - 6 m/s = 6 m/s
This means B gains 6 meters on A every second.
Calculate Time to Meet:
To meet again, B must gain the entire length of the track (840 m) over A.
Time = Total Distance / Relative Speed
Time = 840 m / 6 m/s = 140 seconds.