Two cyclists start together from the same point on a 600 m circular track and ride in opposite directions at 4 m/s and 6 m/s. After how many seconds do they first meet?

Explanation

1. 01

   Riding towards each other, they close the gap at $4 + 6 = 10$ m/s.

2. 02

   They meet when together they have covered one lap: $\frac{600}{10} = 60$ seconds.