Two trains travel on parallel tracks in the same direction. Train A travels at $80,\text{km/h}$, Train B at $60,\text{km/h}$. Train B is $120,\text{km}$ behind Train A. How long will it take for Train B to catch up with Train A?

Step-by-step solution

1. Find the relative speed: $v_{\text{rel}}=80-60=20;\text{km/h}$.
2. Set up the relation $v_{\text{rel}}\times t=120$ km.
3. Solve for time: $t=\frac{120}{20}=6;\text{h}$.

Concept tested: Relative motion of two bodies

Published 7 October 2026 · How this solution was prepared and checked